It is hard to know what you were doing with your antiquated version, because there have literally been thousands of updates since then. (By the way, you are not on version 20.anything. The latest is v19.9.24.)
Most likely, you are not using the reference feature correctly, as it has seen enhancements. You can either enter free text numbers or use the automatic numbering capability. See https://www.manager.io/guides/18764. The latter can be set under Form Defaults, which did not exist in your old version either, if I remember correctly. See https://www.manager.io/guides/14059.
Guides about almost everything can be accessed from within the program. Slide the
Learn how to… switch at the bottom of any screen to the on position to see relevant links from any page. That will be helpful, as so many other things have also changed since you last updated.