In the Snippet+ tool, 3 cutting options are available:
IN SELECTION MODE
Cut (you select the part to be deleted).
To do this, use the "open scissors" 
which has the function of cutting what you have selected between blue and yellow.
Cut out of the selection (you select the part to keep).
To do this, use the "closed pair of scissors" 
which has the function of keeping what you have selected between blue and yellow.
IN BLOCK MODE
Whichever pair of scissors you use, the function remains the same, splitting the track at the location of your reading head.
In this mode, the presence of the blue and yellow lines is for preview only and is not related to cutting.