Resources to learn powerBI

I work in research and impact for a social enterprise and have recently started using powerBI for a lot of my deliverables. I don't come from a tech/software engingeering/data analyst background and everything I know about this software is through self learning from youtube videos and online tutorials.

I have grown to like powerBI, mainly for it's functionality and ease of use, and I want to get better at it. What are some online resources (youtube channels/handbooks/guides/courses) I can refer to to get better at using PowerBI? Brownie points if these resources are free :) Thanks!