Oracle Quality:Mapping bwteeen user defined elements and backend fields

We are on 12.2.3 and defined a collection plan with some elements say userid1 , userid 2 etc .There is a table called qa_plan_chars which stores the maping between the element(prompt) and the backend column like character1, character2 etc that this element value is stored in the table qa_results.Is there any setup which allows you to control which field(one of the character fields in the backend qa tables)  the user defined elements must be stored in or is it random and decided by the system.?

thanks

rahul