From the watch face, long press the middle button to open Settings.
When on the watch face, you can press the lower button and select Control panel from the Widgets to get access to all of the watch settings.
If you want quick access to a certain setting and/or feature, you can customize the upper and lower button logic (from watch face view) and create a shortcut to your most useful setting/feature.
Select Customize in Settings or in the Control panel, followed by Top shortcut and Bottom shortcut and select what setting/feature the upper and lower buttons will have when long pressed.