Wow, I honestly don't know. I had not used my iRig HD for years so had to go find it, and, yep, it does just what you said. I guess someone thought this would be a good idea, but I don't get it. I suppose if you wanted to actually change settings while recording, especially if you've got pedals you want to click on/off it's better. Still, would be nice if it were optional.
Don't suppose you've chased this in the Apple support forums?
I have to say after using a computer DAW, I don't think I could make myself use this for a full project. I like it for quick ideas on the phone, but that's about it. (I was using it on an iPad Mini this time.)
Let us know if you get an answer on how to toggle this "feature."