Change Measurements and Averages

Tap the first box of the reference to open the Reference Editor.
Type the new distance and tap OK.
The Designer asks whether you want to add the difference to all the following references. Answer Yes if the rest of the stage is shifted by the same distance.

Tap the first box of the reference where the stage starts (the one that shows the average, for example S50).
Type the new average and tap OK.

To add an average speed change in the middle of a stage, open the Reference Editor of the reference where the average changes and type the new average: that reference starts a new stage. To remove an average speed change, hold the first box of that reference for 1 second.

Holding the Add reference button (6) for 1 second opens a menu with tools that change the whole roadbook at once:

Adjust references distances (%): multiplies all distances by the percentage you enter. 100 leaves the distances as they are, 101 increases them by 1 % and 99 reduces them by 1 %. Useful if you measured the route with the wrong calibration.
Adjust speeds (%): multiplies all the averages of the speed (S) stages by the percentage you enter. For example, 90 lowers all the averages by 10 %.
Convert metric units (Km/h) to imperial (MPH) and Convert imperial (MPH) units to metric (Km/h): convert the distances and the averages.
Mark as WPT based on GPS error (mts): marks as WPT the references whose GPS position has an error smaller than the one you enter, and unmarks the rest.