When I draft using the beta the game lets me sideboard cards in between the best of 3 in newcomer matches. But once the first round ends it doesn't give me the option to sideboard and gives me the same cards I chose before the sideboard in the next best of 3. Is this how it's supposed to be? Or am I supposed to b able to sideboard Anytime I'm not in a match.
The deck you build after the draft portion and before the matches is the deck you start EVERY match with.
You can sideboard between games 1 and 2 and games 2 and 3 of each match.
Ah I see. Is it the same in non-online draft as well?
It depends on the setting. you have to start with the same deck in all rounds in a competitive-level draft, so it's the same at that level. At FNM-level drafts, it depends on the store, but all of the ones I've been to allowed continuous construction -- sideboard whenever you want.
In IRL drafts/sealed, the deciding factor is whether the event uses decklists or not. Decklists in use = same main deck for Game 1 of every match. No decklist = do what you want. All competitive/professional REL events use decklists. At Regular REL (FNM, prereleases, etc), whether decklists are used or not is up to the discretion of the tournament organizer, so you could just ask ahead of time. For what it's worth, I've never seen decklists used at an FNM, Prerelease, or Launch Party/release weekend limited event, but once in a great while I've heard of them being used in some strange and distant land.
You can sideboard between games 1 and 2 and games 2 and 3 of each match.
It depends on the setting. you have to start with the same deck in all rounds in a competitive-level draft, so it's the same at that level. At FNM-level drafts, it depends on the store, but all of the ones I've been to allowed continuous construction -- sideboard whenever you want.