Yes, if you are familiar with Windows File Explorer and your profile, it's a simple copy/paste item. In the old profile, its name is abook.sqlite and the collected addressbook is history.sqlite. Just copy and paste into the new profile. If you're unsure the disc location of the active profile, do this first: # click help>troubleshootinginformation # scroll to 'profile folder' and click 'open folder' # EXIT thunderbird here # you are now in the profile. Paste those two files here. If the version of thunderbird on old PC was OLDER than version 78, post back for different instructions.