This action will change the default settings. Existing users are not impacted. New users are - they inherit these new settings. Test it by creating a new user, and check the settings.
Now go to YaST -> User and Group Management and Edit an existing local user.
Check their Password Settings tab. I’ll bet they are still set at the old default. Change the settings here, and see what happens!
lol!<<kablooey! your machine will blow up!>><< no, no, just kidding, just kidding.>>
BTW, there is a checkbox to force an immediate change, if you want it.