You can use an extension such as Lastpass in Epic's webstore. 

To backup passwords in order to uninstall and re-install Epic, you can also follow these instructions:
Backup Passwords & Bookmarks.  Open a window navigator, then type %localappdata% and press return. Then open the “Epic Privacy Browser” folder, then open the “User Data” folder, then open the “Default” folder.  Then copy the files (not the folders) in the “Default” folder — particularly “Bookmarks” “Bookmarks.bak” “Login Data” “Login Data.journal” “TransportSecurity” “Preferences” and any other files there.  Copy those files into some safe folder on your system!!