i was given a used mac desktop, but the previous owner cannot remember his admin id and password. Therefore, I cannot make any changes or keep my files, because I have to work under guest. How can I bypass the old admin and create one for myself?
You should backup everything that you have in the guest account and then follow the directions
at > What to do before you sell or give away your Mac - Apple Support
You should backup everything that you have in the guest account and then follow the directions
at > What to do before you sell or give away your Mac - Apple Support
Change Administrator and password
