There is a User Configuration (decl_batch__User_Configuration__c) field on the standard User object. Entering the User Configuration Name from a User Configuration into this field will apply the User Configuration Lines from the User Configuration to the User.
If the User Configuration on the User record is changed, then the User Configuration Lines on the previous User Configuration are removed and the User Configuration Lines on the new User Configuration are applied.
If the User Configuration on the User record is removed, then the User Configuration Lines on the previous User Configuration are removed.
If the User Configuration is deleted, the User Configuration Lines on User records with the deleted User Configuration are removed.
Note: User Configuration deletion can be undone by navigating to Recycle Bin in the App Launcher and restoring the User Configuration record.
If a User Configuration Line is added to or removed from a User Configuration, the change is applied to all User records with that User Configuration.
Note: User Configuration Line deletion can be undone by navigating to Recycle Bin in the App Launcher and restoring the User Configuration Line record.