Oh by the way is Tor really safe? Can my passwords be stolen?
Generally not if you're using HTTPS instead of HTTP.
I just thought if you change your MAC address, it forces your IP to change if it's dynamic.
This is actually, mostly, correct.
You can just reconnect your router to change your ip.
Most ISPs will try to give you your old IP, if possible.
A mac address is a physical address of any digital device; even your smart phone has a mac address.
They are pre-set by the manufacturer.
Pretty much all routers allow you to spoof your MAC address.