How do I change the Daily Budget on my campaign?

To change the Daily Budget go to the Manage Campaigns tab and select the campaign you wish to edit in the left hand sidebar.

Click on the camapign you wish to edit and the bottom toolbar will be visible. Go to Campaign Settings. In the Campaign Settings pane you will be able to edit the campaign name, start/end time and the daily budget. Press Update to send your changes to Facebook.

Read more about how you can edit your campaigns here.