I am near computer illiterate. When I got my new computer, when I was setting it up it asked me if I wanted to run 32 bit or 64 bit. Then it scared me saying 64 bit might have compatibility issues and I would not be able to access all my files. I chose 32 bit to be safe but now the thing is as slow as my very old computer. Will it run faster if I change to 64 bit? If so how do I change it? I HATE windows 8 because I can't navigate on it very well. I miss my windows XP...
Most people get used to Windows 8 after a while. You can look up a quick tutorial to speed up the process if you want (there are many in the Windows 8 forums here at Tom's and I'm sure that I could find you some links if requested). If you're still not getting used to it, then there are easy ways to change the UI to your liking.
Changing to 64 bit shouldn't impact performance much. It might even make it worse.
What computer do you have? Windows 8, although not as light as XP, isn't such a heavy operating system that any remotely modern system should have trouble running it.
Not many programs that work on 32 bit systems will not work on similar 64 bit systems. Compatibility is almost 100%. It's usually only very old programs (XP-era and older) that can have broken compatibility due to them using, like The_Prophecy said, 1 bit code that isn't supported in 64 bit Windows because Windows only supports up to one bit width below the native bit width of the OS. For example, 64 bit versions support 32 bit code and 32 bit versions support 16 bit code, but 64 bit versions don't support 16 bit code.
You would have to completely reinstall Windows to change to a 64 bit flavor. Might want to get a friend who has done this before to do that install for you. They should be able to back up any data you want to keep while they are at it.
Also, the whole reason they said might not have access to all of your files is because 64 bit versions of both Windows 7 and 8 will not run 16 bit executables anymore. These programs are ancient by computing standards (15+ years old when they were first written). Some people still need to run them though, so those kinds of warnings are included just in case.