How to stop scaling beyond the outermost reference lines
This guide shows you how to keep the regions above the shallowest and below the deepest reference line at their original size.
With three or more reference line pairs, the regions beyond the outermost lines are scaled by a straight line fitted through all the pairs. This is usually what you want, but a single outlying pair can then stretch the whole end of the track.
Steps
Untick
Linear fitin the top left corner of the Fit figure. The fit is applied again straight away.
The regions beyond the outermost lines are now shifted to meet them, but not scaled. Tick the box again to go back to the linear fit.