Скачать или смотреть How to change default programs apps on linux from the terminal the update-alternatives command

If you want to change a default program like php version or another app on your linux system without a graphical interface (like on your server)

You can easily do it with the update-alternatives command

Here's how to use it:

First, you can get a full list to see what is your system defaulting to with this command:

update-alternatives --get-selections

and to change any one of the default apps to another version, first install that version, example, if you're running php8.2, also install php8.0

And then type:
sudo update-alternatives --config NAME-OF-APP

example:
sudo update-alternatives --config php

this will give you a list of all php versions on your system and you'd be able to pick one from the list and the system will use that version when its running php tasks (like cronjobs.)