If you choose Call Back as your action, the lead will push to the end of your queue, unless you have chosen a time for follow-up from the drop-down, in which case the lead will be injected to the top of your queue at that time.
You can edit the available options in the follow-up select box from your preferences under the "working"-tab.
Choosing the option "Any time" when selecting follow-up will push the lead to the end of the queue.