Each track has its own volume which can be adjusted by the slider on the track. Click down on the slider and move it left or right.
The volume can be set from 0% to 200%. ( -Inf dB to +6 dB )
Alternatively, you can set the track volume by selecting the menu "Track" followed by "Set Volume" followed by a value or "Set Exact Value..." You can also right click on a track to get the same menu options.
Note on Armed Tracks: The volume slider turns into a red slider and allows you to adjust the recording level. When you disarm the track, the volume slider returns to its original position and color.
Tip: Hold down ALT, SHIFT or CTRL and click drag the slider for finer and more accurate adjustment.