Hi @Charly87 , Dorico automatically updates tied notes and divides them according to the prevailing meter (time signature) and the settings for note grouping set for the flow in Write > Notation Options > Note Grouping. This is described in the result of the topic about inputting ties.
If none of the options there produce the result you want, you can use Force Duration to fix notes - make sure you activate Force duration for notes, then tie left-to-right, as tied notes are a single note in Dorico, meaning the 2nd note gets “eaten” when you tie the first to it. So the settings apply left-to-right.
You can read more about note grouping in the manual here, and in a general introduction here as well.
(Edit: some note grouping options in Notation Options depend on whether notes are followed by more notes or a rest, and produce different results accordingly. So what happens immediately after the notes in your screenshots is important too.)
Thanks for your speed answer, it’s very professionnal ! I will make some “test” with your advice.