Buttons which are labeled like Filter... (with the ellipsis) access menus when pressed; those with no ellipses execute commands directly. For example, click on the Cont. Acq button to turn on continuous acquistion mode; click on the Filter... button to bring up the Filter menu, then click again to actually select a filter. Notice that the Filter menu disappears after making the selection. If you want the menu to remain visible (if you are often changing filters, for example), click on the pushpin icon to pin it to the screen. Click on the pushpin again to close the menu.
