The app has not been working for the last 3 days I've been trying to sign in I've got in now but can't complete invoicing invoicing is starting to back up now what shall

Hello there, gulstankhan.

Let's run some steps to resolve your concerns so you can continue working on your invoices.

You may be experiencing some system-related issues. Let's perform a few basic troubleshooting steps to fix the performance issue. First, let's refresh your QBO app by clicking Help and then Reset App Data. 

Next, clear the cache by going to File in the upper left corner and then Clear Cache. This step will help us clear out the stored files which impact and causes issues in the program.

If the same issue persists, I'd suggest reaching out to our phone support team so we can investigate this issue further. You can do so by tapping the ? Help icon.

I've also added this reference as your guide in recording customer payments: Record customer payments.

Keep me posted whenever you have concerns about recording payments.