Do any of you know how to change hyperlink colors with in a document?

I want to put black back ground buttons at the top of my page and white lettering. I know how to change those to hyperlinks and to choose white to start and yellow when clicked on or active. What I don't know how to do is make the rest of the hyperlinks in the document stay blue and purple when active.

Do any of you know how to do this?

I want one hyperlink to be White with yellow when activated and another one in the document blue then purple when activated.

Thanks for any help