How do I change text color in my Header?

[Canapin (Coin-coin le Canapin)]

I believe the header primary color only applies to the native header of Discourse, not the areas you show in your first screenshot, which are custom.

You probably need to customize this with CSS.

You can go there and learn some useful stuff about it. It will greatly help you next time you need such customization:

Make CSS changes on Your Site

Want to make some CSS changes on your Discourse site but not sure where to start? You’ve come to the right place! You only need to read this topic if you’re very new to CSS. If you already know how to write and add CSS to your Discourse site, then you will most likely not need to read this topic. We’ll cover a few subjects. We’ll start with a brief introduction of what CSS is and some terms that you need to know. We will then move on to how you can add CSS to your Discourse site. Finally…

And be aware of this:

Policy notice: no basic HTML / CSS questions please

We do enjoy helping people with their free, open source Discourse instances, and that is indeed part of our responsibility to the open source community. However: Over time, there has been a constant influx of basic HTML and CSS questions that are taking time away from us helping with more substantive issues specific to Discourse. It’s not a productive use of our time to teach basic HTML and CSS. There are thousands of online resources that describe how to make changes on an HTML pa…