conflicts with multiple monitor/AV receiver

I recently bought a AV receiver to connect all my sources to my TV via the receiver.

I connected my DVD-Player, the cable receiver and my computer with an HDMI cable. Also a stereo cable from my computer to the receiver.

The conflicts appear when I want to use my PC when the TV is turned off. The settings I use on my PC are normally at multiple monitors/extend this display. Everything is working fine when the TV and the PC are on. When I turn off the TV (or only turn on my PC), my settings on the PC changes to extend displays and my monitor of the PC becomes the secondary display how ever the settings were before (only one monitor, multiple monitor, duplicate or extend, main or secondary display). When I turn the TV on, it re-changes and everything is fine.
I have searched for some solutions on the internet but all I found until now are not solving the problem. Solutions like HDMI Detective cost some money (which I don't want to spend yet).

If you guys have any ideas how to help I would appreciate it a lot.

Thanks
Chris

specs:
Win 8.1
Geforce GT 630
AV receiver Onkyo HT-R580 (HT-S5300)