I was having problems with opening multiple windows without getting signed out of QuickBooks each time. However, I was able to fix the problem by first creating a "tab group." Using Google Chrome,

• Right-Click on the tab that you have QuickBooks open in (at the top of the web page)
• Choose "Add tab to group" and give your group a name such as "QuickBooks"
• Right-Click on whichever section tab (Sales, Expenses, or Banking that you wish to open in a new window) located on your QB's page on the left-hand side.
• In the pop-up menu, Click  "Open Link in" and choose the group you just created (such as QuickBooks).  

This will open the selected section in a new window. 

I hope this helps. It seems to work for me in Google Chrome. Please let me know how things go. Best of luck.