Hi kerrie63,
welcome to this Apple (user-to-user) Community!
R: "My Dad needs a custom alarm tone in Assistive Access mode. ..." "When I place his phone into Assistive Access mode - it reverts back to the default alarm tone even though the custom tone is still selected as the sound. Help anyone?
Am no expert in this area, yet your post to the community deserves some response. Fortunately Apple Support documents ways of working with the software, and how to achieve customisations etc. (I'm guessing the alarm tone is used in the "Clock" app ?) The info. below may or may not help you solve your situation, so please let us know if you need more help.
Note: The linked articles and examples below are for iOS18. If your Dad's iPhone uses an earlier iOS version you can select that version at the top of each article, for the most accurate info.
Seems Assistive Access is set up to keep things simple, yet you can customize various things:
Understand certain differences in Assistive Access on iPhone - Apple Support
Eg: says:
"Assistive Access apps have been redesigned for cognitive accessibility and include larger text and icons, more focused features, and customizable options."
How to: Change Assistive Access settings on iPhone - Apple Support
Eg: says:
In the Settings app, you can add apps to Assistive Access and customize them, choose a screen layout, enable or disable the iPhone buttons that control volume and Silent mode, show or hide additional information (such as the time or battery level), and more.
To adjust these settings, exit Assistive Access if it’s active,
then go to Settings > Accessibility > Assistive Access.
All the best :-)