Ok. Let’s go through the faces together.
With regards to both Solar Graph and Solar Dial, the colors are fixed to that blue color. So that’s working as expected.
Meridian has a few layers- you change the dial color to black or white and those are the only options avaible. If you swipe over to the second page of the Meridian face, you can change the complication colors from multicolored (which is probably what you want) or to other colors that basically just change the text of each complication. Can you swipe between the pages?
Infograph and Infograph modular are largley the same as Meridian- changing the color away from multicolor just changes the text of the complications on the face.
You may have more success trying to change and customize faces from the Watch app. Hope this is somewhat helpful. WatchOS 6 is a learning experience for everyone right now.