Greetings @psturmey,

I don't think it's possible to change these via out of the box Designer styling alone.  For that, I recommend trying one of the other themes (I assume you're using Platinum?), or if you're set on a theme, CSS can be changed by cloning and modifying an existing theme, or injecting styles into specific Forms/Views.  The latter is a simple way to test and can be done by adding a <style> tag to an expression on a Data Label set to Literal. 

Inspecting the "Click here to attach a file" text element reveals that it inherits color from the 'file-watermark' class.

You can overwrite the color:

<style>
    .file-watermark {
        color: red !important;
    }
</style>

Same thing for the attachment links, though I would target the classes 'hyperlink static' instead.

<style>
   .hyperlink.static {
      color: red !important;
   }
<style>

Hope this helps,

Jonathan