Copy and paste function acting strange

I am having many problems with this file things just seem to be moving where were they want to- I tried two methods with these pieces of furniture- I held down CTRL and used the move tool but the furniture was inserting half in the floor- then I tried copy and paste and from top view it looked fine- I just looked at it in perspective and the copy and pasted like a ladder. Is there something wrong with my file or just me?

I expect it’s the way you are using the tools and your lack of experience/understanding of them. Considering you are new to SketchUp, why don’t you use a much simpler model to learn how to use the tools? It seems you are setting yourself up to fail at this.

See these video tutorials by Aidan Chopra

Thank you!