If you have filed joint returns in the past you should remain consistent with those returns and keep the order of the names the same. It confuses the IRS and can delay your refund if you change the order of the names.
If this is a first-time joint return, you can clear it and start over......just switching the names will not fix the income information, etc. you entered---that will stay where you entered it.
And....why? It does not matter who is listed first, as long as you stay consistent.
If you want to start over....
If you have not registered, paid or e-filed you can clear and start over
CLEAR AND START OVER
https://ttlc.intuit.com/questions/2586254-how-do-i-clear-and-start-over