The criteria in Personal Criteria library are time-stamped showing the currency of the databank the last time they were calculated. You can automatically update your custom criteria each time you update the TeleChart databank by placing a check mark in the box beside "Update Personal Criteria following download" in the Update TeleChart dialog:
You can also update your Personal Criteria library anytime you edit an existing criterion or create a new one. Click Databank | Personal Criteria Formulas, then click the Update All Criteria button. The program will only (re)calculate criteria that have been edited and newly created criteria.