Right-Clicking and Multiple Selection 

Right-clicking a transaction brings up another menu, which shares many functions with the Transaction Editor. The right-click menu allows you to delete, memorize, show other side, or mark as cleared, reconciling or uncleared. If you are using a single-button mouse then holding the control (ctrl) button while clicking the mouse should have the same effect.

You can also left-click multiple transactions while holding the shift or control keys to select more than one transaction. Right-clicking any of the selected transactions after selecting them will also bring up a context menu, providing only functions that can be applied to multiple transactions at once.