i have one radio button which passes value for 2 multiselect.
if i change value in the radio button i want to change the value in multiselect to default value or reset the preferences to empty..
In order to do this you will need to write some logic in your dashboard to handle different tokens. Essentially the result is that you need to change the token represented for the multi-select.
Take a look here for for some information which should hopefully help: docs.splunk.com/Documentation/Splunk/latest/Viz/tokens