Have sound bar remote pairing code, how to input it?

I have a Yamaha sound bar that I have the correct remote pairing code for, but can’t get to a screen where I can manually input it.  I just upgraded my cable box and remote. In the past when I’ve changed out my remote or box I’ve been able to press a combination of buttons on my remote to get to the input screen, but I can’t remember how. I called Xfinity but was told I’d have to call Yamaha even though it’s the Xfinity interface that won’t let me manually enter the code (Xfinity’s remote pairing wizard searches and can never find the working code).  Can someone help?  Thank you!