Edit a manuscript after submit and approve it
I think that submitting a new manuscript will just confuse them. The version you submitted will be checked and reviewed. You will get back a report and, hopefully, a request to update and resubmit changes. Make your changes then. 

If that isn't enough to satisfy you, then contact the editor of the journal and ask for advice on how to proceed. But what you have discovered is pretty common. 

The journal needs, for now, a stable version that can be sent to reviewers. You are just at the beginning of the process and will have time to fix things.