In Alabama, you must be 19 or older to legally change your name. Probate Court has original jurisdiction over all matters regarding name changes. Each county in Alabama has a probate court, with the exception of Jefferson County, which has two.
A Petition for Name Change must be filed with the court in the county in which the Petitioner (the person filing the petition) resides.
There may be filing fees of approximately $25-$100 dollars set by the court, and many counties require background checks, which also have an additional cost. The most commonly required background checks are an Alabama Criminal History Record (ALEA Report, linked below) and an FBI background check.
The Court has discretion to grant or refuse the requested change of name.