My thumbnails do not show the entire contents of the forms they are capturing. 

Unfortunately not all component vendors support the default capture method of Visual Forms. If you are coming across components that do not capture correctly you need to make sure the Force Screen Capture option on the Capture page of the Options dialog is checked. 

Capture Options Help 

My thumbnails do not update when I save my forms. 

If your thumbnails are not updating when you are saving your forms, make sure you have the Capture option set to automatic. 

Keeping your forms updated