This can be applied to new parameters, or when editing existing parameters.

Here is an example of editing an existing parameter from the web: 

Choose the parameter you want to change, click the 'lock' symbol to unlock:

Change the time & frequency from the dropdown menus:

DO NOT manually clock the 'lock' symbol after making this change - locking will be done automatically when you click "DONE".

Here is an example when adding a new parameter from the iPad: