It's nice to see you again here in the Community, @aaronsonrepairsl.
I'm here to help make sure you're able to enter an amount when selecting a products/services on an invoice in QuickBooks Online (QBO).
Just to confirm, when you say you're unable to enter a dollar amount, is it greyed out? Any additional information will be much appreciated.
As an initial troubleshooting step, try logging into your QBO account using a different or a private browser. There are times that the browser is full of frequently accessed page resources, thus causing some unusual responses. To use a private browser, here's how:
Once logged in, try to create a test invoice to double-check. If it works, return to your default browser and perform clear cache. Every so often the cache can become overwhelmed with older data which can potentially cause viewing and performance issues. Clearing it will refresh the system, and you'll be able to work with a clean slate.
That should get you fixed right up. Please comment below to let me know how things look after giving this a try. I'm always here to help. Have a wonderful day!