Older version don't run

Hi, i am using Mac 10.15.5 and i have noticed that whenever i update software to new version, old one stops working. whereas it was not the case b4. could keep both copies of software and both functional. Is it a new thing that once upgraded older version won’t work?

The issue is not that the older version of the application does not work. What you are seeing is that business data files that have been opened by newer versions of the software cannot be opened by older versions of the software. In other words, the application will run, but you cannot access your business data.

The reason is that newer versions often change the structure of the database to accommodate new features. Once changed, the old version of the software cannot access the business because data is no longer in the same place.