Sorry we don't support search through all forms.
You can do search inside of the single form, in the Response tab.
You can submit your idea to the ideas section. We use that to help guide what features we work on.
How do u search inside single form?
When in the View Responses tab, use Edit->Find menu (or Ctrl-F) to open "Find" toolbar where you can type text to seach inside of the response table.