There is no such thing as openHABian 2.4, it’s 1.4.1 or 1.5.
You can use the menu to change between latest stable, latest testing (milestone) and latest snapshot releases, but you cannot select any older version. If that’s what you want you need to download the package (see @rossko57’s post) and use your package manager or see here how to install older version from the repository.
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