This is the standard behavior for Voyager template. If you need to tweak the color, you can always add the custom css codes into the custom css file,

[gist]
body a, body .uk-link {
color: blue !important;
}
[/gist]

Thank you this worked but I don't see the underline. Do I miss something?

You can try this following custom css code :

If you would like to all the link show the underline, you can use this.

body a, body .uk-link {

    text-decoration: underline !important;

    color: blue !important;

}

If you would like to all the link show the underline on the article content only, you can use this.

body .tm-article-content a {

    text-decoration: underline !important;

}