At any level of license upgrade, the FCC 605 form has a box to check if you want a new , if appropriate, callsign (Like Amateur Extra). Where a nice one by two is cool for getting your extra, everyone on the air already knows you for your existing call. As for me, I don't ever want a change in callsign. KC2PBJ is known on 15, 17, and 20 as Peanut Butter and Jelly and that's what I'll stay. Back in 1960, my novice WV2OGS was old grungy socks.