Is there a trick to matching bank transactions with expenses? For the banking that doesn't match I can see them in expenses, but not as an option when trying to link.

This is happening to about half of my transactions. I am new to the banking side of Quickbooks so I'm hoping it's something silly and simple that I haven't or need to do. Some of these will be new ones to add that have slipped the system - but some I know are on there in my expenses. I'm very confused and frustrated.