Change code editor variable highlighting colour
Variable colors share settings with table, object and other names. So you can change the text color using Identifier:


  


Just note that it will also affect table names, column names etc.


  


For the highlighted color of identifiers and variables, use Selected Text. The highlights will use a slightly muted version of that color.

And no, these are not my current settings, and I only kept them that way long enough to grab a screen shot...