To Edit or Add symbols in your video:
Select the video you want to edit to view edit options
Select Edit Symbol
Select Show Symbols to view symbol library
Scroll through the symbol library to find the symbol you want to use
Activate your symbol
Tap and hold your screen to record and overlay the new symbol
Stop recording at any time to unselect the symbol
Play the video to the end to finish editing
Confirm the warning message for the system to process and save your edited video