When using quickbooks from phone or tablet can not convert estimate to invoice.

Hi and welcome to the Community space, @Liberty11.

Allow me to share some information about your concern where you can't convert estimate to invoice using QuickBooks from phone or tablet.

Please be aware that there is an ongoing investigation regarding the issue of where you're unable to convert estimates to invoices using the mobile app. In the meantime, the best course of action would be to reach out to our Customer Support Team and request them to add you to the list of affected users. Once you are added, you will receive email update and be notified as soon as the issue is resolved.

Here's how to contact support:

1. Sign in to your QuickBooks Online company.
2. Select Help (?).
3. Select either tab to get started:

• Assistant: Get quick, personalized answers. Select a suggested option, or type a question or topic you need help with. If you decide you need further help, you can still Talk to a human.
• Search: Search the QuickBooks Online knowledge base directly, or select Contact Us and choose a way to connect with us:
  • Start a chat with a support expert.
  • Get a callback from the next available expert.
  • Ask the community to get help from businesses like yours.

You can also check this article for more details and be sure to review their Support hours to know when agents are available.

Moreover, I suggest converting the estimate to an invoice on Android devices and the browser version of QuickBooks Online using a browser. 

To learn how to convert an estimate into an invoice you can check this article. Also, if you decided to learn how to set up estimates in QuickBooks Online: 

• Convert an estimate into an invoice in QuickBooks Online
• Create and send estimates in QuickBooks Online

I'll be here to provide more assistance with handling your estimates or invoices in QuickBooks Online. Have a pleasant day. Keep Safe!