QUESTION How to change menu active label?

[bacmid]

I installed MagicForest Theme instead of Lucid. 

The original menu active label was "current active" like this:

Code:

<li class="index current active">
     <a href="xxx">Home</a>    
</li>

but the new theme need "uk-active" label, where can I replace it?

Thank you very much.