Can I input a different license number if another one has been on my computer for another person. I bought another turbo tax and code but how do i get it to take code?

Why would you do that?   (and no, you cannot do it).   The download you already have on your computer can be used to prepare and e-file up to five federal returns and the state returns that go with them.  Every version of the download has all the forms and all the schedules.  There is no need to download another version of the desktop software with a second license key.

If you have more than five returns to file, the other ones can be filed by mail.  The five federal e-file list is an IRS limit.