Change published date to 12 hour time Right now my nodes say published by "author name 19:02". How can I change it to display 12 hour time 7:02?
It uses the default date format of the site, which is medium. You can configure that at admin/settings/date-time and choose a format which uses am/pm.

You can also implement hook_preprocess_node() in your theme or module and then override the 'submitted' variable set by template_preprocess_node(). That allows you to use a different date format just there.