Looking for a little help;

I recently purchased a MacBook Pro after using a MacBook for 7-8 years. I've planned to transfer all the content from my old MacBook to the new MacBook Pro. To this point, I think I have completed all the proper steps but I face a new issue that I can't resolve on my own.

I connected the 2 notebooks with a hardwire cable and set the old MacBook as a target drive. All content was then transferred to the new MacBook Pro. However, when I have to access the old content, I have to log out and switch users.

Can someone offer me some help to integrate all my content onto one drive?