To change objectives, click on the third icon on the left and then select your objective from the options shown.
The second icon allows you to select your light path (brightfield or epifluorescence), and to control the shutters. It also allows you to select between the DsRed filter and the blue/green/red filter.
The fourth icon, showing the stage, is where you'd go to to change the speed of the stage x/y controls. You can also use it to change the speed of the Z dial on the mini set of dials to the left of the microscope which has only one z dial.
If you need to Köhler the brightfield light path, the first icon on the left lets you adjust the brightness of the illumination, and the Aperture & Field diaphragms.
