My browsers won't use my full screen resolution and also use different resolutions between them

Solution 1:

Possible Problem

This is most likely an issue caused by Window 8.1 "Display Scaling" feature. See a relevant post in the Google Chrome forum.

Possible Solution

Try disabling this feature for your browsers. For example, locate the Chrome executable which is commonly found in %ProgramFiles(x86)%/Google/Chrome/Application/. Right click the file, select "Properties" and then under the "Compatibility" tab tick the box saying "Disable display scaling on high DPI settings"

Solution 2:

Well, it’s pretty obvious this is yet another example of DPI scaling gone horribly wrong.

Chrome is party to blame too. According to this article, there are (well, were) some possible workarounds.

• Disable DPI scaling in Chrome’s compatibility settings (Properties on executable or shortcuts)—last resort “solution”
• Go to chrome://flags and enable experimental Windows HiDPI support. (Gone now, apparently)

• Load the following .reg file:

  Windows Registry Editor Version 5.00
  
  [HKEY_CURRENT_USER\Software\Google\Chrome\Profile]
  "high-dpi-support"=dword:00000001

A word of warning though: HiDPI is under development and has issues. If you cannot live with that, I suggest you try an alternate browser like Firefox. It’s supposed to have better DPI scaling support.