I'm confused. I keep hearing that everyone must do something to upgrade to BIP 148, but I don't know what it is? I hear others saying that BIP 148 will not happen? Either way, all I have is Bitcoins on Poloniex. What should I do? Backup my bitcoins? What is the safest way? Is it safe to just leave them in Poloniex? Should I download Bitcoin Core or something?

Thanks in advance, I'm really confused. 🙁