Different volume bar locations on iPhone 13 Pro Max with same settings

Both phones have latest iPhone software update. Accessibility setting are the same with no changes from default settings. My husband’s volume bar used to be on left side of screen but at some point it changed to the top of the screen on his phone. How can he change it back to the left side of the screen? He did have his phone connected to his hearing aids but he has disconnected them. Could this have changed the location of the sound volume bar?

[Re-Titled by Moderator]

Original Title: iPhone 13 Pro Max volume bar at top of screen on husband’s phone and at left side of screen on my phone. Volume settings are the same on both phones. Why the difference in location of the volume bar?