I have "returning memories" and "assassins of kings" in the prologue without the green tick.

And now I am at chapter 1 "rough landing" ?

how can I complete the prologue then ?

Those quests span multiple chapters, it's a bit obvious IMO.

ok thanks for the info.
i'm new to witcher series.
i thought prologue need to be completed then proceed to chapter 1.

To be fair, it's only truly obvious if you read the full quest notes, which can be lengthy. If you are just glancing at your quest list like a grocery list, it can be a bit more confusing. Witcher 1 was like this as well. I love it, personally, but do get tripped up myself from time to time.

One of the great things about this game. You will make a choice, and won't reach the effect until a while down the road.

A couple of quests in Witcher 2 span more than one chapter. If you are not sure, download the guide if you bought the game on GOG. It is helpful.