Good Afternoon, @TAMMY9524. 

I hope your week is going well so far. After researching your question further, I've discovered that the option to save a category to a vendor isn't available at this time. However, I'll send feedback to our Product Developers so they can consider this feature in a new release for QuickBooks. Developers take the time to look over all request and try to make the product better and easier to navigate through for every customers. Here's an extra link that may come in handy: Categorize online bank transactions in QuickBooks Online.

Let me know if there's anything else I can help you with. Wishing you continued success. Enjoy the rest of your week.