Why do my new invoices still show RC in my business number after I changed it to RT

Hi there, 

Thanks for joining the QuickBooks Community. It's important you're able to change the business number and have it reflect on your new invoices. Don't worry, I'll be happy to point you in the right direction. 

Based on the details you've shared above, I suspect you may be experiencing a browser-related issue that's causing the issue. Clearing cache and cookies helps with fixing most browser issues. You can do this by following the steps in this article: Clear Cache and Cookies. I encourage you to give this a try on your browser when you get a chance. In case you aren't being affected by cache and cookies, could you walk me through the steps you're following to change the business number? 

Feel free to let me know what happens. I'll be here in case you have other questions.