Where in the filesystem are settings saved? Namely ADB backup password
In my stock Android 4.2.1 the file responsible for holding Desktop backup password seems to be /data/backup/pwhash.

I took a backup of it, renamed it, restarted the device, and the password was reset to empty. Now I could create a new password from the Settings easily.

In CM12, I had to rename two files, namely pwhash and pwversion, and everything went well after a reboot.

Note: I noticed file modification in /data/&lt;FOLDERS&gt; to proceed and ultimately reach my conclusion, which of course works here.