In some themes, like more, you can edit some of the hyperlink characteristics. However, I prefer adding CSS to the themes custom CSS textbox. I do this myself, as follows:
/* To make hyperlinks a different color than black */
a:link { color: #990000;} /* unvisited link */
a:visited { color: #cc6666;} /* visited link */
a:hover {color:#990000;} /* mouse over link */
a:active {color:#009899;} /* selected link, complement of maroon */