For delicious yoghurt you need 1 Bifidus natural yoghurt from Migros (these are particularly suitable, or rather I was advised to use them) and 1 litre of whole milk. Stir both elements together, fill into the jars, close with lid and put into the machine for 9 hours. I always use a new yoghurt for the production, you can also use a homemade yoghurt, but they became a bit sour, which tasted a bit less to me. A tip: buy reserve jars so that you can make the production a little faster. Keep 3 jars ready for this, and it is also a reserve if one should break.

We tried making yoghurt with ferment and found that liquid remains on top of the yoghurt. In addition, we had the impression that it was not appealing in terms of taste because of the milk to be used.
We have had good experiences when we prepare the yoghurt with a natural yoghurt and let the process run for 9 hours. This gives a good and sturdy and fine yoghurt.

Great, thank you very much for the answers!

We take a sugar-free natural yoghurt and 1 litre of milk, mix it well, fill it into the 8 jars, put the lids on loosely, then put it in the heat for 15 hours. After that we have perfect, firm yoghurt. Have fun and enjoy.