When selecting sales, and clicking on invoices, the system just freezes/hangs on and just sits there invoices any ideas?

Hi there, @imran1.

If QuickBooks Online keeps freezing, it could be a browser-related issue. I have troubleshooting steps to help resolve this. 

To begin, you'll need to open your browser in incognito/private mode. This mode doesn't use the existing cache data files to load a webpage, which can cause unexpected behavior if too much information is saved.

Here are the keyboard shortcuts to open a private browser: 

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

If you're able to do the task successfully with a private browser, I suggest clearing your browser's cache to start fresh. If it's the same, you can use a different browser such as Google Chrome, Internet Explorer, or Mozilla Firefox.

Please feel free to let me know how it goes. Hope you have a great day.