It's hard to say what you have to do: so many variables, and not much info. Indeed, the AdvancedEditor is the tool to use.

WHAT you have to change depends on what is incorrect. Suggestion: make a backup of your plans and work on that file to see what needs to be done.

1 - check height of levels and thickness of floors
2 - check height of walls
3 - check length of walls
4 - check size of furniture (doors & windows are furniture)


Where it says "check" you should read "check and if necessary correct by multiplying or dividing by 10". When changing furniture make sure you put a checkmark in "Keep proportions".