You don't say what version of Archicad you are using - you should add this to your signature in your profile (link at top of this forum).
In 18 you can right click in your floor plan and save as a 3D Document.
Then create a view in the View map of this 3D Documents that saves the scale, layers, pens set, Model view Options, etc.
Now you can add this to your layouts - just like you do for any other views.
The scale (and other settings) will be remembered at all times.
Barry.
One of the forum moderators.
Versions 6.5 to 27
i7-10700 @ 2.9Ghz, 32GB ram, GeForce RTX 2060 (6GB), Windows 10
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