I keep getting spam show up on my Facebook sent to all my friends. When I looked into how it was sent I noticed that it was sent via cell phone.
I've changed all passwords to all accounts but it is still happening - how can I stop this?
One extra thing I'd do is change your settings so that you can't update Facebook from any cell phone.
Then check that the correct cell phone number is associated with your account.
Check your Facebook Applications Settings, and remove access to your personal data if you're unsure (particularly your cell number, etc.). There are few apps that absolutely have to have your cell phone number IMO. Also check your privacy settings, as these can also have an effect.
Check the settings on various applications. many of them access your friends list and have permission to send emails/post to your walls. Un-check those options if you are able or do what I did and uninstall those applications.
that person is probably sending updates to your upload by email address.
so you would need to refresh your upload via email address, which will change the address.
you can find out what your upload by email address is here: http://www.facebook.com/mobile/ (at the bottom left of the page) then click "find out more" then click "refresh your upload email" that will change your upload by email address which will stop anyone being able to update your facebook via the old address, which has probably been compromised somehow.