Why refresh rate drops to 30Hz?

I have two screens in my computer. They are both set to 1920x1080p 50Hz. If computer is on and i switch off another or both screens, and after then turn them both or just one on, refresh rate is 30Hz. Why? And is it possible to make 50Hz default after screens are set off and on again?
One of those screens are projector so thats why i need to switch it off sometimes.

Hi @Phiit9, and welcome!

In order for us, or anyone for that matter, to be able to provide assistance, more information is necessary. To that end, please see:

Hope you manage!