How do I upgrade ? And if I download the 4.0.3 version , it just doesn't open in my computer .
What operating system are you running? Newer versions of Electrum have some issues with older versions of Windows, as per the electrum download page:Quote from: https://electrum.org/#download
Old versions of Windows might need to install the KB2999226 Windows update.
Basically, Windows 10 should work without issues, Windows 7 can be quite problematic to get running properly, since version 3.0+ of Electrum
