If the OnFocus - Select All property is selected, when the TextMeshPro - Input Field is selected all the text within the field will be highlighted.
If the Reset On DeActivation property is selected, the caret will reset to the default position at the front of the text.
If the Restore on ESC Key property is selected, the text will reset back to the default when the escape key is hit. The default will be either an empty string or whatever is entered in the Text Input Box when the scene starts.
The Rich Text property means that any rich text tags to be accepted, and the Allow Rich Text Editing property allows the user to enter rich text tags within the field.
