How to reset App Store password. Have other devices that will connect but iPad will not

There is no specific App Store password.

The password is the one for your Apple ID, and changing it changes it for all devices using the Apple ID.

You can log in to https://appleid.apple.com to change your Apple ID and its password.

Read here once you change it: What to do after you change your Apple ID or password - Apple Support

Change your iCloud login information - https://support.apple.com/KM205092