Hello there, Nelly111S.

There are two ways to import customer addresses into QuickBooks Online (QBO). You can import them using the Excel file or use the Connect your Gmail account option when creating an invoice.

However, if you're not seeing the latter option, we can try performing some basic troubleshooting steps to verify if it's an issue with your browser.

Let's start by using an incognito or private browser when adding a customer from the Invoice tab. This is to see if the issue is caused by an overloaded data in your default browser's cache. 

You can use either of the following shortcut keys:

• Google Chrome, press CTRL  + Shift + N
• Mozilla Firefox: press CTRL  + Shift + P
• Internet Explorer: press CTRL  + Shift + P
• Safari: press Command + Shift + N

If it works, I recommend clearing your browser's cache to refresh your browser and delete files that are affecting the browsing performance. Otherwise, try using other supported browser.

Let me know if there's anything else I can help you. I'm here to keep helping. Have a good one.