how do i change the windows app password, it isnt the same as my account password.
The app password, is only required if you have set it. By default there is no password set, so you must have set one.
Can you remember doing this and did you make a note of it ?
In order to change that app password you would need to enter the original, catch 22.
It is possible but not easy to do:
See: Regaining access to the Avast program without a password
See the ‘Regaining access to Avast Antivirus without a password’ section at the bottom of that page.
You would need to download and save the Avast Uninstall Tool (in a location you can find it).
Note doing this would effectively reset the new installation to default settings.