Changing the post displayed in slider

Hi, I think I am stuck doing something wrong with the posts displayed in the slider on the homepage. For some reason, some of them are working just fine and taking all the changes I am making, but 2 of them just won’t respond :(.
I can’t change the numbers of the posts and choose others either.
Can you please offer some help?

The blog is

Many thanks,

Hi Maria

May I know how to replicate the problem? which slide is not responding?