The problem with two monitors

Not understand the question. First you need to configure the system to fly on the 1st monitor and what is the BIOS and system selection. When everything works you can connect a 2nd monitor.Using the right mouse button choose display settings ,then in the column multiple displays - for example, extend these displays, etc. you probably enabled when both monitors are selected to do the main TV and the only show on the TV -turn off your system, unplug from the outlet the TV, turn on the computer. and now the computer monitor will be the primary.

mibr777
If you have 2 monitors connected to two different connectors HMDI and VGA for example that the old BIOS will be displayed with the VGA because this connector has priority and I don't know this is something you can fix or not