Okay - had to go back to a version of QC10 we have to check this.
The way it works is as follows. When you add a Component to a Test Script in the Test Plan it will create an entry for all the parameters of the Component. In the Promote Parameters option box you have 3 options - don't promote, promote all, promote selected. All this does is let QC create a parameter variable for the selected parameters. Then you can adjust the parameters opening the Component Iterations dialog. Here you have three choices - 1) set a fixed value; 2) set a Run-Time parameter - either the name used if you promoted or anyone name you have created; and 3) set to blank - which means that you don't want to use it.
So in answer to your question if you leave the parameter variable value blank for any parameter then at execution it will not ask for a value.