You can switch the Scales and Modes - mode on (Setttings → Scales and Modes). The Display Notes box will be replaced with this more complicated box. Note: the Play Scale button is grayed out and becomes available after you made your choices.
The many possible scales that are used in music are divided into groups. The Commonly Used Scales are exactly that "commonly used". 7 Note Scales are those where you need seven notes (e.g. C- D - E -F - G -A -B the C-major scale). The one octave higher C is not counted but will be included. Pentatonics are those with five notes and you may want to explore the Misc. Scales category. For the 7 Note Scales you can further select a mode (default is the Ionian). The usual selection with Shift-Click gives you access to one or more octaves to be included. After your choices are made you should see a box of this type:
The Play Scale button is now enabled. Click on the button and depending on your workspace selection (Frets, Strings) the scale is played.
The button Show Notes will show the note names in their position on the fretboard. Switch #/b allows switching back and forth between sharps and flats.
Note: The Flashcard buttons are enabled and you can practice a chosen scale in flashcard mode.