How do I change the Litchi app voice?

I’ve downloadedthe Litchi app onto my Mavic 2 Pro which I use with a Smart Controller.
In an effort to understand the garbled voice, I’ve downloaded the Google Text-to-Speech engine along with the Google Play Store. Unfortunately neither appear on the “desktop” of my controller, despite being visible in the apps list. How do I go about sorting this problem out. I’ve tried so many things !

Thanks for any help.

Google text to speech is not a real app, just a speech engine that runs in the background and that Litchi will use if available. It should normally just work after you install it, though it may depend on the language you use.