Order of players actions in Mansion of Madness 2nd edition
Player 1 has to take 2 actions before the other players can do something.

From the rules reference page 24:


  During the investigator phase, the investigators each take one turn in the order of their choice. During an investigator’s turn, that investigator performs up to two actions.


This means that when each player takes a turn they do two actions and they must do all of their actions before another player can take their turn. You can select the order of that each player takes their turns and change it each investigator phase.