Thread:Smash The Echidna/@comment-32712012-20180318102749/@comment-32712012-20190428211534

Click to the user's contributions on the target wiki, then click "user rights management", then check the boxes for the powers that you want to give that user and hit "Save user groups" (optionally typing in a reason for doing so first).

An alternate (but equally effective) way of getting at this is to go to Special:Userrights on the target wiki, type the user name into the box that appears there, and then continue with box-checking and so forth as detailed above.