To open your show for editing, at the main menu click 
underneath show thumbnail to bring you to Open show Window, then click 
Editing show is very similar to creating new show. You can go back and forth between the same five steps you create your show by modifying an existing settings. Click on any of the five buttons at the bottom left corner of the application window to choose the step you want to modify.
The five steps are:
To add more photo, delete an existing photo, reorder photo, change photo caption, crop, rotate and adjust photo brightness
To apply photo effect.
If you create your show using a theme template, this step will let you choose other theme template.
If you create your show using a customize template, this step will let you change your template customization.
To add more/delete or modify clipart/speech bubble/sound/recorded sound.
To change a music, transition setting, title and credit.
When you finish editing your show, click Finish Editing button at the bottom right corner of application window. You might be asked to save your show and then you will be directed to Opening show Window.