So the cboTherapist at the top you need to change the Row Source to...
SELECT tlkpTherapist.tTherapistID, tlkpTherapist.tLast FROM tlkpTherapist INNER JOIN tblClinicTherapist ON tlkpTherapist.tTherapistID = tblClinicTherapist.ctTherapistID WHERE (((tblClinicTherapist.ctClinicID)=[Forms]![frmSearch]![cboClinic]))
ORDER BY tlkpTherapist.tLast;
As for the second one where the Search button won't work. Well not sure what you are looking and no matter what it doesn't have TherapistID or FullName in the first column of the the combo box, see below. You have Clinic Name...
SELECT tlkpClinic.cName, [tFirst] & " " & [tLast] AS FullName, tlkpVisit.vName FROM (tlkpTherapist INNER JOIN (tlkpClinic INNER JOIN tblClinicTherapist ON tlkpClinic.cClinicID = tblClinicTherapist.ctClinicID) ON
tlkpTherapist.tTherapistID = tblClinicTherapist.ctTherapistID) INNER JOIN (tlkpVisit INNER JOIN tblClinicTherapistVisit ON tlkpVisit.vVisitID = tblClinicTherapistVisit.ctvVisitID) ON tblClinicTherapist.ctClinicTherapistID = tblClinicTherapistVisit.ctvClinicTherapistID
WHERE (((tblClinicTherapistVisit.ctvVisitID)=[Forms]![frmSearch]![sfrVisitTherapist].[Form]![cboVisit])) ORDER BY tlkpTherapist.tLast;
So, to fix that one, change the cboTherapist Row Source to...
SELECT tlkpVisit.vVisitID, tlkpClinic.cName, [tFirst] & " " & [tLast] AS FullName, tlkpVisit.vName FROM (tlkpTherapist INNER JOIN (tlkpClinic INNER JOIN tblClinicTherapist ON tlkpClinic.cClinicID = tblClinicTherapist.ctClinicID)
ON tlkpTherapist.tTherapistID = tblClinicTherapist.ctTherapistID) INNER JOIN (tlkpVisit INNER JOIN tblClinicTherapistVisit ON tlkpVisit.vVisitID = tblClinicTherapistVisit.ctvVisitID) ON tblClinicTherapist.ctClinicTherapistID = tblClinicTherapistVisit.ctvClinicTherapistID
WHERE (((tlkpVisit.vVisitID)=[Forms]![frmSearch]![sfrVisitTherapist].[Form]![cboVisit])) ORDER BY tlkpTherapist.tLast;
Then adjust the lines behind the Search button to...
If Not IsNull(Me.cboTherapist) Then
strWhere = strWhere & "([vVisitID] = " & Me.cboTherapist & ") AND "
End If
And change these Properties in the Property Sheet for cboTherapist...
Column Count: 3
Column Widths: 0";0";2"
That should do it.