farmboy84
If you find that you did not use the best and/or correct project preset for your project after you established the project preset, the Adobe party line is that you start a new project.
But, I have found it is possible to change project settings in this situation under certain circumstances. The technique involves editing the Notepad document of the saved closed project. After weighing all factors, you may find it easier for you to start a new project. Please review the details of the technique, and then decide what is in your best interests.
But, I would ask "What is the project preset that you have, and to what do you want to change it?"
Be advised that the project preset set by you (manually) or the project (automatically) should match the properties of the source media. What you do with the export settings in another matter for further discussion.
Please review, consider, and then we can decide what next.
Thank you.
ATR