How to change colors in editor, not be selecting themes

I just installed ubuntu-mate last night. I have been using ubuntu, then xubuntu for many years. It seems that I cannot change the colors in the editor, just select from one of the themes. Are the themes programmable?

Do you mean syntax highlighting in Pluma text editor? That would be the same as gedit.

For background, character color and highlight selected line, it only offers some fixed themes, But I cannot choose my own. The gedit had a tab for ‘fonts and colors’ but the demo did not select them.

It has to be an xml file. Located here

Or change the current settings