Have 8 year old 32 sharp aquos and just hooked up LG 300 watt soundbar thru optic cable but my xbox one and fire stick do not seem to be working with the soundbar.

Are there any other connector inputs on your soundbar?
If not you may need to purchase a digital to analog converter. Fiio makes one as do many other companies. Easily found on Amazon for about $20.00.
You hook up your tv's RCA audio output to the RCA input on the converter and then the optical cable to the converter then to the soundbar. That's how I would solve this issue.

If you are connecting the soundbar to your TV with the digital audio cable, make sure to select "D IN" using the source button on the soundbar. Bluetooth (BT) is a separate source from another device. (phone, etc.) The TV will need to be set to use the digital audio output and probably PCM format. (?) The subwoofer is preconfigured at the factory to mate up with your soundbar. (See below instructions - your soundbar includes the amplifier:)

Digital audio output setting:
After connecting an amplifier with digital audio input and
external speakers as shown, you should set an audio
output format compatible with the programme you are
watching or the device connected.
Go to "HOME" > "TV Menu" > "Setup" > "Option" >
"Terminal setting" > "Digital audio output" > select
"PCM" or "Bitstream".
NOTE
• When set to "Bitstream", Dolby Digital is output when the Dolby
Digital or Dolby Digital Plus audio formats are received. When
set to "PCM", PCM is output no matter what audio formats are
received.
• When set to "Bitstream", HE-AAC audio formats can be output
as Dolby Digital.

Disconnect the HDMI cable and use only the optical cable for better sound. Don't connect both at the same time. Once the set sees the optical cable it switches to it.

Just used a plain VGA cable to hook it up,it will work just fine.

Yes you can but it won't be Hi def. It sounds like you're trying to connect the cables to the Hi def input (Red, blue, green, white and red for the audio) That's not the right place to connect to.

Almost every Sharp TV has DIGITAL AUDIO OUTPUT - optical interface.
You will need TOSLINK cable to connect soundbar to the TV.

Hook it in the antena hole,go to nenu set up cable in setting.

When you are changing channels you are using the tuner of the sat reeiver. the tv does not know you are changing a channel . It is just receiving a constant signal from the SAT receiver. I would suspect a problem with the receiver. Try another one first .

is the switch set to hdtv on the cables... and are the display settings in the dashboard set to hd

good day sir! are you sure your cables are in good condition?