A scalar parameter is one named value for the whole project, written with an @.
A scalar parameter is a named value declared on the project and written @Name in a formula. It holds one value at every slice and every step. Its type is number, true or false, or text.
scalar parameter @Discount = 0.20 scalar parameter @OpeningCash = 5000 scalar parameter @WeeklyPayroll = 1200
A parameter's value is known while a formula is translated, before any SQL is written. That is what lets a parameter fix an offset, as in Revenue[x=-@Lag], or name a member, as in plan=@FocusPlan.
A parameter can change a number. It can never change what a formula means.
A value that differs from slice to slice is not a parameter. Put it in a table as a column and read it under the table's name, such as scenario.growth. Calcbird reads that value only when the query runs.