“Render As” settings are different than “Project Poperties” settings.
Your project is set up so that all files match the original settings. My primary use for this is to have stills match the project setings.
when it’s render time though, this can be set to anything you desire.
I’m away from my computer right now so the following is from memory.
After selecting your desired output type (in your case, QT Pro H.264 Codec), click on the “Custom” buton and then the Audio or Video tabs. Make the necessary changes and save this as a preset (high, medium or low).
The next time you go to render, these options will appear in the drop down menu once you select the render “type”.
HTH.