To update the text for all performances you can go to the “Edit Internet Settings…” window (you can select this from the “Web” menu along the top)

Navigate to the “T & Cs / Information” tab and it is in the bottom window – “Performance Extra Information”.

This will update the text for all perfomances.  To edit text for specific performances only, see below.

To update for specific performances, navigate to the performance in the Day Planner.

On the Internet Sale - Extra Info tab, check the Override performance extra information HTML, and enter the text you wish to appear here.  This will replace the default text (set above) with what you have entered here.