Sorry, I don't speak Thai and Google translate isn't very fluent. But from the screenshots I can tell where in the game you are having issues.
Once you adjust the riddle, you need to give two clues about Nell. I only see one Nell-related clue in the screenshots you attached.
You need to have solved Nell's small secret, and you need to have heard the story of how Samarra adopted Nell. With Samarra, you have to "talk about samarra" repeatedly - each time she tells you another bit of her story, and the clue about Nell is in the very last bit. If she says she doesn't trust you enough to tell you the next bit, you need to do something to impress her on the training grounds. Pay attention to Samarra's story, and the adjustments you need to make to the riddle become quite obvious.
