Are you talking about Create Space or KDP-Print? They are different, and CS is superior.
Assuming you really mean CS, by far the easiest is to use their templates, which have the margins pre-set. Do "copy" with your Word document, then "paste and match formatting" of the text into the template.
Ebooks don't have left and right pages, because it's just reflowable text, so I'm not quite sure what you mean, unless your book is fixed-format?
I'm intrigued by your comment that in your eBook the left and righthand pages are different. Ebooks don't use left and right pages so I suspect you mean this is what you see when you view your Word document on a screen? If this is the case then there is a formatting problem somewhere which I think you need to address first as this is likely to lead to problems with the paperback.
I'm going to guess and assume you are using KDP Print Beta for the paperback, because I think you have to use a PDF for Createspace - though I might be wrong, not having used CS. What you need to do is format your Word document to the correct physical size, for example if the book is going to be 9" by 5" then you must set the page size in Word to 9" by 5". You also need to use mirrored pages, that is ones where there are left and right hand pages and this is how you set the gutter and margins. You can also do the same with footers so the page numbers are in the outside corners, if that is what you want to do.
This is all explained in the guidelines, page 18 onwards. https://kdp.amazon.com/help?topicId=A1MMZZIUU7LTIB
An alternative approach is to download a template from the Amazon site and use that but it might be better to work out how to format the Word doc manually. There is another thread on here about the template and the problems someone had with it - which were overcome in the end.
If you are getting the error message "trim is incorrect" then this suggests you do not have the page size set correctly.
It would help if you could confirm whether you are using Createspace or KDP Print.