By default, autocompletion search will include Term names as well as Synonyms. The other options to choose from include:
Term name - The name of the term itself.
Synonym - The name of the synonym for a term.
Definition - Partial matches are based on inclusion within the definition of a term.
DBXref - Looks for matches within the DBxrefs for a term.
Obsoletes - This is an optional setting to be used in combination with one of the settings above. It will look for matches to term name, synonym, DBxref, or definition in terms that are marked as obsolete, in addition to non-obsoleted terms. In order to select obsolete search, you must have at least one of the other four search options selected. (By default, Phenote does not search obsolete terms.)
To change these settings, simply check on/off the desired option in the Settings menu:

You can also save your autocompletion settings in your configuration file
using the autocomplete-settings parameter, e.g.
<autocomplete-settings term="true" synonym="true" definition="false" obsolete="false" dbxref="true"/>