Remove airpods frome ONE phone and not the other

I have an old phone and my current phone. I listen with my airpods to things on my old phone. How do I get my airpods to ONLY be on this phone, and not on my active phone? They keep connecting to my active phone, and then I have to deal with them connecting randomly and also they show up as options in audio when making phone calls, EVEN WHEN THEY ARE NOT CONNECTED to the phone! I have accidently clicked this option instead of SPEAKER and then took me a bit to figure out why I could not hear the phone call!

I have

I have been doing this for a couple years now, and this recent changed that I cannot have the airpods set up on one phone and NOT ever device on my apple id.

Do I need to create a new apple id?

I do see that I have different devices in my bluetooth devices list on each phone. How do I get the airpods to behave the same way - one one phone and not another?

thanks for your expertise!

EDIT I do have "Calls on other devices" set to OFF