Reposition - Use one finger drag it to your desired location

Resize - Use two fingers to pinch in or out.

Rotate - Use two fingers and rotate

Move on the timeline - Use one finger to drag the entire preview earlier or later

Adjust the duration - drag either end of the text bar to make it smaller or larger

Edit the spelling, font, or color - Tap "Edit"

Delete - Tap "Delete" or "Delete All"