didnt you add the tip=”” part to your theme’s index.php? I downloaded the theme youre using and looked — that tooltip code isnt included in the theme.
At any rate, the edit location for the DEFAULT index.php thats included in the zip is here:
<a href="<?php the_permalink() ?>" rel="bookmark"><?php the_title(); ?></a>
Replace that with what I pasted above.
—
As for a plugin, if youre inclined to use a plugin for something as simple as this, have at it. The plugins are here, browse away:
https://www.ads-software.com/extend/plugins/
Lastly, I notice your listing “something” in the sidebar thats somehow related to posts. And your also listing recent posts. Making those tooltips work will take more editing than ive already said, so if your hesitant about what little i’ve already suggested, Im not going to explain the others changes. Theres also no telling where it (the tooltips edits) will end.
You might just want to find another plugin that affects all links generated by wordpress and ANY and ALL plugins and mash that up to make the tooltips work through it.