There is a way to follow specific users, but if your goal is to effectively bookmark a thread, you can click the "Follow This Thread" button in the bottom right of a thread. You can then see threads you've followed here:
https://www.elitetrader.com/et/watched/threads
I do agree that being able to see likes that you've given would be nice, but I believe the describe function satisfies your goal of effectively bookmarking threads.
EDIT: Maybe I've misread. Do you want to see threads that OTHER users have followed/liked or just your own?