I had used the forum search and found nothing. At least not a thread with extensive information.
:
When you zoom out, the canvas does not get bigger. To expand to the left, for example (from the program's perspective the negative axis), you have to draw something.
I searched for the plugin and could not find it. However, I found that there is also an official plugin with which you can really rotate individual walls, rooms, objects arbitrarily.
On the SweetHome3D website under Plugins, the AdvancedEditing. That works. I only have the other as a plugin here. With it, you can basically rotate everything at once. All levels in one go by 90° per step.