Stole key fob - SOLVED

[Doubeleive]

I lost a fob to my '16 Tahoe LTZ. Bought a replacement on eBay for cheap, and programmed it myself using the procedure in the owner's manual. So, now my fob shows up as "driver #3", and the seat, pedal, steering and mirror presets don't recognize it.
Oh, well. I did save a bunch of money after all.
But it sure would be nice to have my pre-sets back again.

yours is a different generation and different procedure, but you should be able to repeat the procedure from scratch and have your #1, #2 etc back to normal.
they upped the security on the 2015, then again in 2018 and more since then..