When playing a riff (a melody at particular fretboard locations), you may want to know what scale it is using.
Once you know the scale, it is easier to expand on the riff with improvisation, or to work out chords to use with it if you are songwriting.
Step-By-Step
Step 1
First of all, you need to be in Relations View. Check the bottom of the workspace and make sure that the Relations tab is selected. If it isn't, click on it.
Step 2
Relations View can operate in three different modes. We need to make sure we are in Scales and Fretboard mode, with any of:
Relations Bar: 
Menu: Relations-Scales and Fretboard
Step 3
We also need to remove any filter setting which might be showing overlay labels on the Fretboard. You can do this with any of:
Tool Bar: 
Keyboard: Ctrl+Shift+F
Menu: Filter-Remove
Step 4
Now, click on the Fretboard in the locations used in your riff to add green blocks. If a location is used more than once, don't click it again, or this will remove the green block.
You should end up with a display similar to that shown.
Step 5
Once all your fretboard locations are indicated, the Scale Matrix will contain a green dot for all scales which contain the notes in your riff.
In this case, there is only one, and we immediately know that we are using a D Major scale, as shown.
Step 6
If you select this cell in the scale matrix, the fretboard will display overlay labels which show the notes or degrees of the D Major scale.
You should notice that all the locations in your riff are labelled in this way.
You can have the labels indicate either notes or degrees of the scale using:
Relations Bar: 
Menu: Filter-Overlay-Note Labels
Relations Bar: 
Menu: Filter-Overlay-Degree Labels
See Also