I can't remember password backup

From: IIf you can’t remember the password for your encrypted backup - Apple Support

"You can’t restore an encrypted backup without its password. With iOS 11 or later or iPadOS, you can make a new encrypted backup of your device by resetting the password."

1. On your device, go to Settings > General > Transfer or Reset [Device], then tap Reset.
2. Tap Reset All Settings and enter your device passcode.
3. Tap Reset All Settings.
4. 
   
5. Follow the steps to reset your settings. This won't affect your user
6. data or passwords, but it will reset settings like display brightness,
7. Home Screen layout, and wallpaper. It also removes your encrypted backup
8. password.
9. Connect your device to the Finder or iTunes again and create a new encrypted backup.

You won't be able to use previous encrypted backups, but you can use

the Finder or iTunes to back up your current data and set a new backup

password.