Are you talking about the sub-menu which are displayed on hover.
If yes then you need to change the event that is applied there ie. as of now its showing on hover so you need to change the js from hover to onclick.
As impulse is a paid theme so can't tell you the exact js to be changed without having access to it.
So if you are ok then you can provide access to me I can help you out.
|a minute ago|