I Have a fossil 10 atm watch & the date doesn't change automatically so i change it manually but then half way thought the day it changes the date

Your watch is 12 hours out of step.

The date changes every second time the hour hand passes 12 O'clock.

Your watches' second pass is at midday instead of midnight, so to make it operate correctly, you need to wind it on 12 hours. The date will then change at midnight.

You have your watch set to the wrong AM or PM as it thinks midnight is during the middle of your day. Note that mechanical watches especially self winding "Automatic" watches spread out the time change throughout the night. Also note that you do not want to make day/date adjustments with the crown in the middle position during the night as it will damage the watch mechanism if you try to adjust the day date while the watch is trying to change them itself, some watches will have a red markings on the dial between midnight and 3 to indicate when not to make day/date adjustments. Also note though it is standard to advance the date (day of month) by rotating the crown counter clockwise in the middle position, adjusting the day of week varies from rotating the crown clockwise in the middle position to pushing the crown in like a button when it is in it's inner most position. The rotating the crown clockwise in the middle position sometimes does nothing or manually winds the spring which is also why expensive Seiko's which have the manual winding of the spring function do not have a day of week display, just the date display (day of month). The inexpensive Seiko 5 sub brand and of course the Quartz watches can have the day of week display (Seiko 5's you often push the crown like a button to advance day of week but you often get a generic Seiko manual especially if it's a display model and the clerk repacked it with the wrong manual, that says to rotate the crown clockwise in the middle position, that fooled me for 30 years).