How to make all sides vertical?

[Higgsino]

Hello,

I am currently building a guesthouse. I have erected all four walls and now intend to ensure all sides are vertical. The problem is that if I make one side vertical, the other changes, even if I brace it. I have screwed the walls together, perhaps I could remove that until the roof is laid, which should hold it in place. However, it feels like a pretty bad solution.

Any tips on what to do?

 

[Stefan N]

But how do you set the braces if they do not keep the wall plumb?

 

[Higgsino]

A strut in each corner (approximately 1+1.5m long)