Using the wrong version of a spreadsheet is one of the ways errors can occur. The situation is exacerbated if you have many users using different versions of the same spreadsheet.
Let's define what we mean by a "version." A version is a code, usually a number that indicates the stage of development in a spreadsheet.
What I have seen is version numbers in this format: 1.0 Major changes to a spreadsheet would be indicated by changing the first number - 2.0. Minor changes are indicated by changing the second number - 1.1, 1.2, etc.
You may not choose to use this format. That is fine. However, whatever you use, you must be consistent to ensure all understand which version is the current one.
Here are some other guidelines to follow:
Your code should indicate which is the current version that users should have.
Have some way to indicate if a version is in development or has been released to users.
Create a new version code whenever you update formulas or the structure of your spreadsheet. This is helpful when you test because it is easier to compare the new version to the old one.
Keep the newest version in a separate folder until it is ready for release.
Make sure your spreadsheet has a version history tab. This should include the version number, the date of a version's release, and a description of all changes that were included in each new version.
Do not delete any older versions. Keep all versions and releases in a secure place for future comparisons and reference.
Clearly label the release and date to avoid using old versions in error.