The Change Label tool has a Label Properties dialog but the options are greyed out.
How to access them?
Your layer has to be in edit mode to enable the tool.
All the parameters in the Change Label box are data defined fields, so you need to have fields corresponding in your attribute table.
After creating the new fields in the attribute table, go to the proprieties dialog, and set up the fields you want access.
For exemple, for the X coordinate :
The "X coordinate" of the Change Label box is now editable.