I use an Nvidia GTX970 graphics card with proprietary driver. The configured resolution is 3840 x 2160, which is a little hard to read on a 24" monitor.
I can change the resolution to 2560 x 1440, using the GUI tool, but I can't make the changes permanent because this must be done as root, which this app does not support. (So I have to do it again with each boot.) So I either need somehow to use this tool as root or make the changes manually, editing the config file directly. What should I do?