Are other people getting a message saying this quote number already exists after you have selected a new transaction? and then end up losing the entire quote ?

Greetings.

We can perform a few straightforward troubleshooting procedures to enable you to aid this error encountered within the quotes in QuickBooks Online (QBO). 

Let's try logging in with an incognito or private browser. Please see the following shortcuts:

• Google Chrome: press Ctrl + Shift + N
• Mozilla Firefox and Microsoft Edge: press Ctrl + Shift + P
• Safari: press Command + Shift + N

Once done, try to check the customer section if you can see the quotes. If the issue persists, return to your default browser and perform a clear cache to refresh the system. However, if the error persists, try using other supported browsers.

Once everything is good, you can refer to this article on how to make a quote: Create and send quotes in QuickBooks Online.

If your customer plans to pay you in the future, you'll have to record them in QuickBooks. See this page for your guide: Record invoice payments in QuickBooks Online.

Get in touch with us if you still have queries in QuickBooks Self-Employed. I'm looking forward to hearing from you.