Only one person can use online banking at time. If QuickBooks is in multi-user mode, when you start using online banking, you are asked to get exclusive use of the feature. No one else can use online banking while you have exclusive use of it.
When you are done, release your exclusive use again so that other people can use online banking if they need to.
To do this task
Go to the Banking menu, click Online Banking, and then click Release Exclusive Use.