- To upgrade you don't have to uninstall the old version. Just install the latest version and it'll upgrade you automatically. It'll also find your wallet files automatically and use them.
That only works if you upgrade to the same "type"... If you have been using a "portable" version (like the OP), and you install the "installer" or "standalone" version, then it won't find your old wallets. Likewise, if you have been using the "installer" or "standalone" versions, then try using the "portable"... it won't find your old wallets.
Remember:
- Installer/Standalone versions use the "Electrum data directory\wallets" folder to store wallets.
- Portable version uses "Electrum executable location\electrum_data\wallets" folder to store wallets.
So, if you switch type, you either need to copy the old file to the appropriate location... OR you need to manually find and open that file from within Electrum using "File -> Open"