Hey Todd,
Thanks for posting and welcome back 🙂
What you describe is definitely possible using jQuery. You’ll first need to identify the category ID by visiting Events > Event Categories and hovering over “Delete” on the category you want as the default when users submit events. You’ll see text in the bottom left-hand side of your browser window containing tag_ID=3. Grab whichever number is where the bolded number is above.
An example of what the jQuery might look like:
jQuery("#tribe_events_cat-6").prop('checked', true);
If you need a bit more assistance on how to go about inserting jQuery into the Community Events submission form, this article may help. Please note this type of support is outside the scope we’re able to provide, so you’ll have to take the reigns from here.
Best of luck and thank you for choosing PRO!