I am managing to figure out most things by trial and error but this has me at the moment. I am not sure if I am missing a setting or just what I need to do.
Do you prefer trial and error instead of the using the manual included with the program, (Help section)?
Then you are missing a wonderful resource.
The manual is a PDF file so it includes a "Search" feature => just search "align
" and voilą!, you will be directed to page 56 where you can see the different alignment options. You can use the solutions according with your necessities.
As a general rule, the chapter called "Edit Menu", starting in the page 53 of the manual, explains how to take advantage of the different editing tools included with the program: these tools are necessary to use the program. In you case, I'd suggest that you check the "Copy to floor" tool (page 58 of the manual) so the walls will be reproduced perfectly aligned.