- Is there a way to change the range of calendar years without disrupting (for the moment) the platform?
- Do I need to follow the build / version history for updates?
Howard is correct, Moodle 2.5 hasn't been supported for years, you should plan to upgrade the site to a supported version. Upgrading will require some planning, check the documentation and post questions on the forum if you need help. By performing a test upgrade first – i.e. make a copy of the site and perform the upgrade steps on this first – then you can resolve any upgrade problems before upgrading the live site.