How to change color of pool grout on coping ?

Painting a grout tile line requires paint specifically made for grout. It's more of an epoxy colorant than a traditional paint, and once cured, it will last for many years. ... Regular wall paints are not intended for use on grout and tend to peel off or not adhere at all

Go to a paint store (not big box) and tell them what you want to do. They will help.

This stain should work for you: https://amzn.to/2ZPXrHB

I tried to paint mine in the past and it didn't last long at all.

Hope this Helps! Jeremy - https://pahjodesigns.com

They do have grout paint at the regular tile store

I have stained and painted grout. Not sure how it will hold up with the sun but I'm sure it will work, especially if you seal it.

There is grout paint

Hi Marsha, hope this helps you out, https://www.tilecleaning.org/how-to-darken-grout.htm