Not able to access account. Need new password to be accepted.

To sign in, add your account
You can add both Gmail and non-Gmail accounts to the Gmail app on your iPhone or iPad.
On your iPhone or iPad, open the Gmail app Gmail.
In the top right, tap your profile picture.
Tap Add another account.
Choose the type of account you want to add:
If you use iCloud, @me.com, or @mac.com accounts, you may need to enter specific settings or an app password.
If you check work or school emails through Outlook for Windows, select Outlook, Hotmail, and Live.
If you don't see your email service, select Other.
Follow the steps on the screen to add your account. If available, tap Try Gmailify to get Gmail features with your added account, like spam protection and email categories.
reference: https://support.google.com/mail/answer/8494?co=GENIE.Platform%3DiOS&hl=en

Try deleting the gmail account from your iphone mail. Then, add it back

on the iPad, goto settings. Then E-mail, contacts, agendas. there select the yahoo account. Then press account. There you can change the password.
After you changed the password the iPhone will check if you did it right. If is accepts the code, you can leave the settings and in the e-mail app you now can read the mail.

Fix Mail Apps and Devices Show Incorrect Password Error After Enabling 2...
[Fix] Mail Apps and Devices Show Incorrect Password Error After Enabling 2-Step Verification in Microsoft or Gmail Account "2-step verification" is an important security feature which protects your online account whether its your email account or a social networking account. It asks for an extra security code each time you try to sign in to your account. This security code is sent to your registered mobile phone or alternative email ID.
Recently Microsoft enabled this 2-step verification feature for Microsoft accounts which are used for emails, Windows 8, XBox, etc. On the other hand Google is already providing two-step verification in its Gmail service since long time.
If you enabled 2-step verification feature in your Microsoft or Gmail account, you might be facing a weird issue. If you try to access your email account using an email client such as Windows Live Mail, Thunderbird, Microsoft Outlook, etc, it'll now allow you to sign in using your current password. It'll show you an incorrect password error message even if your password is absolutely correct. The same problem will also occur if you try to sign in using your Microsoft account in devices such as Xbox 360 or Android smartphones.
Now the question comes why does this problem occur? Why do these mail apps and devices not accept your correct password? The answer is very simple. These mail apps and devices were not designed to ask you for the extra security code which is required for 2-step verification. Since these apps and devices don't ask for security code, the 2-step verification procedure is not completed successfully, hence you can't sign in using your credentials in those apps and devices.
So what's the solution? The solution is very simple. Every company which provides 2-step verification feature, also allows you to create special passwords for these mail apps and devices. You can create separate passwords for each app and device and then you can use that special password to sign in to those apps or devices. Now those apps and devices will accept the new password and will allow you to access your account without any problem.
So if you have enabled 2-step verification feature in Microsoft or Gmail account and if you are facing login password problems in mail apps or devices, you just need to create above mentioned special passwords or codes to sign in without any problem.
Just follow these simple steps to create app passwords for your Microsoft or Gmail account:

A. Create App Password in Microsoft Account 1. Open your Microsoft account security settings page by clicking on following link:
Open Microsoft Account Security Settings Page
2. You'll see "App passwords" section at the bottom of the page which shows following information:
Some apps and devices don't support security codes. In these cases, you need to create an app password to sign in. 3. Click on "Create a new app password" link and it'll immediately provide you a new password generated randomly.

Now you can use this new password to sign in to a 3rd party mail app or device.
B. Create Application Specific Password in Gmail Account

1. Open your Google account settings page by clicking on following link:
Open Google Account Settings Pag
2. Now click on "Security" tab given in left-side pane. Scroll down on the page and you'll see "Connected applications and sites" section at the bottom of the page.
3. Click on "Manage access" button and it'll open a new page showing following information:Some applications that work outside a browser aren't yet compatible with 2-step verification and cannot ask for verification codes, for example: email programs including Outlook, Apple Mail, or Thunderbird, older Android smartphones. To use these applications, you need to generate an application-specific password. 4. Type any desired name in given text box and click on "Generate password" button.That's it. It'll immediately provide you a new password which can be used in any mail app or device to sign in.PS: If you want to remove or disallow any mail app or device to access your account, you can remove existing app password or revoke access from devices using the same account security settings pages as mentioned in above instructions.

how that helps good luck.

If you need to change your password, look for something like "I forgot my password" or "I forgot my username" - even better, get to this page:

Reset your password

You will receieve a new password on your email. Be sure to also change your email password, and every other account that used the same pass you had on AOL, otherwise the hacker may still access your accounts.

Maybe, try setting-up a second Gmail account, then send transfer) your emails from the old username account to the new username account. If this works, then either try deleting the messages from the old gmail account and transfer the messages from the new gmail account back to the original gmail account ... or ... just delete the old gmail account if you successfully transferred them to the new gmail account.

Maybe you need to drop all your accounts and create one by one in your imac
In iPad only you need to download the app GMAIL and thats all

Hi Thomas you can reset your password at gmail.com and then re-enter the Password on the iPad under > Settings > Contacts, Mail, Calendar.

This should allow you then to receive email as long as the account has been setup as a gmail account on the ipad.

After creating new account on google.com.tap settings on iPad,tap mail,tap gmail to delete old account..tap mail again on top left then tap add account,tap gmail then enter info for new account.