Currently the system narrows a drop down search, as you type, based on finding the matching data anywhere in the field, like a wildcard search.
Change the system to narrow the search starting at the beginning of the field. For example; if I type S, the system should return only the records starting with S.
If an embedded search is needed, allow a wildcard search by using a wildcard character such as asterisk. For example to find all records with an S anywhere in the data, enter *S*