pware gave good advice letting you know where to find the instructions.
Basically you move your userdata folder to the D drive and then simply point the app to it. After you get your data folder on D then:
- Start TRS-19
- From the opening screen select "Trainz Settings
- Click "Install" tab
- In the top field (Local Data Folder) just enter the path of your data folder (or use the nav tool to show TRS19 where the folder is)
I have several installs so I give my data folders meaningful names like: Standard Install, Plus Install, Plus Beta Install. The name of the folder doesn't have to be "cryptic" like the default is.
After doing this Quit and Restart. You may get the "set graphics" screen just as if it were a new game. If so, verify the path to D drive data folder is good and then Quit and start again. I find that sometimes I have to restart twice for it to really find the data folder.
I also run TRS-19 from my C drive. You might feel more comfortible doing a fresh install of the app on D and then just point it to your data folder with the restart(s).
As always, leave the install on your C drive intill you verify the folder copy to the D drive works as intended. Alway have an "escape" plan (ie: backup!)