Of course we recommend leaving automatic updates on so that you get the latest features and bug fixes. We can't support old versions and there may (unlikely) stability issues. If you anyway would like to disable automatic updates, then do the following:
Open the App Dir via the Help menu (you may have to press Alt on Windows/Linux to see this menu):
2. Create a file called settings.json in this directory if it doesn't already exist.
3. Set the content of this file to:
{ "autoUpdate": false }