Hello Everyone.
I have only used Ubuntu and Kubuntu in my entire life (my AGE is 17)
Yesterday I Installed Elementary OS in my desktop which has an i5-2320 processor powered by a 4 gigabyte ram with no external GPU.While installing I was not able to install the Operating system in high resolution for reasons unknown.And after installing,I decided to change the resolution from 720p to 1600X900 pixels.When i clicked the display button,I got no other resolutions other than 1280X720,800X600
pixels.I used the xrandr command,which worked but as there was no instruction for elementary OS I didn't know how to save the settings

so you got the desired resolution, but it reverts back to lo-res after logging out/in?

then you just have to make sure that xrandr command gets executed every time you log in.

most desktop environments have a menu entry called "Startup applications" or "Autostart" - try adding it there.

The Thing is I don't know how to do that.And I'd like to mention one thing now,yesterday I updated everything using the "softwares and updates" app and when I logged in just a few minutes back I got 1600X900 resolution by default and in the display section it was displaying "Samsung Electric display" and I got all the resolutions that this monitor could handle,but to check whether it works or not I restarted my PC and then again everything was back the way it was.And in the display section it was displaying "Unknown display".Please do tell me how to run those commands in the start of the PC