Add text manually to your video
Tap Text on the bottom bar
Start typing and tap Apply
Edit your text
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"