If you're happy with a particular deployment, you can graduate that deployment, and use it as the basis of your deployment into Mainnet. Other than selecting a different network in MetaMask, the steps are the same! To graduate a deployment, it depends which view you are using on the cards or table.page:
Under the Staging column, click on the 3 vertical dots of your chosen deployment. Select the GRADUATE option from the menu to use the same build as the basis of your deployment into Mainnet. After you're done, you'll see a new deployment in the production section.
If you're using the TABLE view, you can simply click on the ACTIONS dropdown, and click Graduate on the deployment of your choice.