Mike
If you have software is it possible it does the same as the app? I know they can be daunting to use and I usually ask my 28yr old son to sort out my difficulties, and I have used computers from their inception!
There must be a modelling club of some sort fairly near, I have flown aircraft and raced cars and find they are all willing to help a fellow modeller of any type. Model trucks seem to be popular at present and the local leisure centre may allow use of their indoor halls. Might be worth asking to see if there are any locally.
You could look (as a guest) at
https://model-boats.com/ and look at Model Boat Clubs to see if there is a club near to your location.
I do hope you manage to sort soon.
If at the end of the day a solution can not be found you may want to look at the FlySky FS-i6S. My club raffled a set at Christmas and I was so impressed I bought one for myself. All very modern and touch screen and has many of the facilities of my Taranis. Easy to program and cheap receivers. I like Fly Sky as they are manufacturers and downloads are available from their site.
Good luck
Dave