I can't tell you how long I've been looking for how to do this one thing... Because it's embarrassingly long. 😥😥
So, to avoid people from getting into the same boat of shame as me, I made this post às my first.
How to change your voting power on Steem:
Simply hold the upvote button and don't let go until you see a slider. Unfortunately, the is for the mobile version on esteem, I'm still trying to find out on main website.
If anyone knows, please post it/
You're welcome ; )