The
only site you should ever be using is electrum.org.
Back up your wallet files.
Uninstall your current version of Electrum.
Download the latest version of Electrum (3.3.8 at time of posting) from
https://electrum.org/#download.
Verify your download by following the instructions here:
https://bitcoinelectrum.com/how-to-verify-your-electrum-download/Install or run your new Electrum version.
Open your wallet files as you would do normally.