How do I accept user inputs or page context to populate a widget's data service parameters?

I have a data service with parameters, but I can't figure out how to use it in a widget so that it doesn't just always use the default parameters.

For example, is there a way to allow the user to input the value for "accountid" or for "accountid" to be automatically set to the customer number when viewing a particular customer record, that way the widget shows something besides the default data service values?