Due to the various side effects a TV power cycle was having on my apps and desktop I eventually realized that turning off and on the TV caused Windows 10 to trigger a change of resolution and/or font size/DPI.
After some research I forced the same DPI for all my displays, virtual and physical by doing the following:
- Go in "Control Panel\Appearance and Personalization\Display".
- Click on "set custom scaling level".
- Set it to whatever works for you. 100% was working fine for me.
Here is a very interesting link regarding that resolution change issue when disconnecting a display, read through the various solutions suggested as one of them may work for you:
http://superuser.com/questions/267086/how-to-stop-windows-resizing-when-the-monitor-display-channel-is-turned-off-sw
Here is a link on how to adjust scaling:
http://www.tenforums.com/tutorials/5990-dpi-scaling-level-displays-change-windows-10-a.html