I’m glad you like your Resound app. I’ve been impressed when I’ve looked at it, but wondered how long I’d continuing use it after the newness wore off. Could the feature you mention be accessed via the buttons on the hearing aid instead?
For the app to be truly useful, not just a novelty, it has to be fast and reliable, unlike say the ReSound Android app. There’s also the issue of reaching the app quickly. Pattern unlock on Android is fast, and so is Face ID on iPhone. You have to set up your home screen so the app icon is right at hand. And the phone itself has to be newish and fast.
With my iPhone X in my hand (so, not counting drawing from my pocket), I can unlock the phone, open the ReSound app, and set or clear Speech Clarity, in a few seconds. That’s fast enough to make it truly useful for me.
The buttons on the aids can change the volume or select a different program.