How can I change the first bubble?

You cannot change the first bubble in Ideta for the moment. But there is a workaround.

You can copy your current first bubble in order to safeguard the content.

Then, you can edit the first bubble and you can link it to the copy for example.

I also recommend to make your first bubble a comparison bubble that leads to the same bubble to matter the result of the comparison. That way, you can change it more easily next time :