Here's some links in case you haven't got this sorted RudeBoi, theme change is no hassle as long as you can access the save files created by the editor,
https://www.gtplanet.net/forum/thre...es-android-tablet-phone.335346/#post-11007961 this thread should help you locate them, and then you can upload your .Bin file here: Gran Turismo Path Editor - Web Editor & Mods and at top of the page you can edit theme number to whatever you want, change track width and bank height.
Theme numbers are:
Death Valley =1
Eiffel =2
Andalusia =3
Eiffel Flat =5
Then when your done just click the download buttons (.meta as well) at bottom of the page and copy the new files back in the Track Editor, (you either overwrite, rename or delete the originals obviously)
Just be aware that if you download the edited .Bin and .meta to the same folder the originals were uploaded from it will rename the new files (something like
"C--yourfilename.bin" and "yourfilename (1).meta" so best to download them to a different folder.
Hopefully I've not missed anything......
You've probably sorted it now, but someone else may find this helpful anyway.