If I understand the question correctly, it sounds like you have one train (the one that will increase speed) on a track fed by a fixed voltage TIU channel and the other train (the one that won’t increase speed) on a track fed by a variable voltage TIU channel (with zero voltage). If so, you need to first push the track button, select the appropriate track and use the thumbwheel to adjust the voltage. You can also change variable channels to fixed channels. Then you can select the engine and use the thumbwheel to adjust speed. You can’t get rid of SMPH. That displays how fast the train is going and is used to help you control speed.
Sounds like you are new to DCS. I recommend you get Barry’s book.
