The symbols allow you to do amazing things, for example edit 3D text created with "Ctrl + J" and not with a 3D "fx".
Type the text, make it a symbol.
"Ctrl + J", move the copy very slightly in the desired direction, then repeat "Ctrl + J" as many times as necessary to have the desired effect.
To modify the text, take the "Text tool", select the letter(s) to be changed and type the new text.
The filling and contour of the text can also be modified.
EDIT
I had made a GIF file to make it less heavy on the forum but it is almost unreadable, so I put the link to the WMV file for those who are interested:
https://www.cjoint.com/c/IHet1HUrGbdOn the page obtained, click on the red button to download the file.