No, you can't change the timezone on Metatrader. It is set by your broker.
Some brokers have different GMT offsets on different servers - you'll need to ask your broker.
It sounds like you're using the MetaQuotes demo server. That isn't a real broker.
I suggest you choose a few brokers (we can't make any recommendations on the forum) and open a free demo account with them to see which you like.