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

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"

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.