Hi henriettaprice,
Basically, what I had done is duplicate an existing icon, replace the icon in .svg format.
Changing the SVG format image icon may be a bit complicated.
You have to go through step-by-step and read carefully (restart all over again if necessary).
A) Follow TyW’s original comment thread thoroughly.
AND WHEN YOU SEE A HUGE ICON…
B) Go to my comment dated and timed 07-06-2020 09:15 AM. and read slow, and implement carefully.
Else, you may want to try quipcorp’s answer on 11-20-2020 12:01 AM which uses PNG format.