Modules & VBA :: Text Font Color Based On Tab Selected?

We have a navigation page with 5 tabs and several navigation buttons underneath their respective tabs linking to reports.

In the main part of the navigation page we have 17 search parameters (text boxes and combo boxes)that the user can use to sort through all the reports we have in the different tabs.

What we would like to do is to have the label text to change to "red" if one of the 17 fields are "required", remain "black" if it is included in the report but not a mandatory search parameter, or turn "light grey" if that parameter is not included in that report.

For example:

My search parameters are: people, phone, and cars

If I were looking at a report of people that included addresses, phones, etc...name and phone would be required search parameters. However, even though I can search by car, it is not in this particular report and the label text should be greyed out. (If the actual text box could go inactive that would be even better).

I have read about buttons being turned colors based on a drop down box choice, but I have not been able to find anything about using a navigation tab subform button to make the colors change in the main navigation form.