Ordering Columns

In Query Editor, bring up your query with the raw data. From the menu, select "Add Column" and then "Conditional Column". In the dialog, you can give this a name like DeptSort and define the conditions. Just keep adding rules until you have all of your values covered. Here is an example of what you will end up with (this is the code that will be written for you):

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45WcnRJLUgsKslNzStR0lEyMlCK1YlWikIRNAaL+aKImZiABSNRBM2MlGJjAQ==", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type text) meta [Serialized.Text = true]) in type table [Departments = _t, Incidents = _t]),
    #"Changed Type" = Table.TransformColumnTypes(Source,{{"Departments", type text}, {"Incidents", Int64.Type}}),
    #"Added Conditional Column" = Table.AddColumn(#"Changed Type", "DeptSort", each if [Departments] = "ADepartment" then 4 else if [Departments] = "ZDepartment" then 2 else if [Departments] = "MDepartment" then 1 else if [Departments] = "YDepartment" then 3 else 0)
in
    #"Added Conditional Column"

After that, you can use Sort By in the Data Model.