I dont remember If I downloaded the Standalone Executable or the Windows Installer when I installed the 3.3.6 version. Does it matter and can I download either one to perform the update?
It does not matter. If you have wallet files stored on your hard drive both the stand-alone or the installed version will be able to open them, no need to re-enter your seeds with either choice. The new install (or stand-alone) will look for the wallet files in "C:\Users\\AppData\Roaming\Electrum\wallets." If you stored your wallet files elsewhere you'll have to browse to that directory.
I prefer the installed version for convenience and OS integration, but it really just comes down to personal preference.