How to Open a Bigger sized Window or viewport from one room to the next

[SilentSlayer]

How do I open a bigger sized window (viewport) from one room to the next? For instance, if the first room's (the main menu's) viewport is 1500 by 1500, and you clicked "Start Game" (which takes you to another room) the next room is still 1500 by 1500, even though I set its viewport to 1500 by 850. How do I fix this? Thx!

 

[PlayerOne]

If you are using GMS2 you can use this function to resize the viewport:

room_set_viewport()