TV12 on Windows 10 Phone changes resolution of target desktop.

G'day from Sydney, Australia!!

I frequently use TV12 on my Windows Phone (Lumia 950XL) while travelling, to access my office workstation which has a Dell U3415W monitor running at (native) 3440 x 1440 resolution. Of late, whenever I log-in to the workstation from my phone TV12 changes the remote desktop resolution of its own volition (to 1280 x 720 IIRC), and I have no way of controlling this behaviour or resetting it. Does anyone know of any way to LOCK the remote desktop against being changed by Teamviewer 12?