Method two: From the Mouse Modes toolbar, click the and left-click and drag the mouse to adjust the window width (left-right motion) or the window level (up-down motion).
Method 3: place the cursor over the yellow W/L text and complete the following:
Figure 1. W/L active annotation located in lower left corner of viewport
Middle-click and drag right to left to change the W/L values.
Left or right click to view a menu and make a selection.