Is there a way to select only the keywords term set for this field? I don't want the people seeing all the term store in the field
You can open the field settings page.
In the Term Set Settings section, select Use a managed term set, and then do the following:
Click the arrow to the left of the Managed Metadata Service application that displays in the box to expand it and browse for the term set you want.
Continue to expand nodes until you find the term set or term you want. Click it to select the term set or term.