unfortunately my posts aren't sorted by date and I don't know why.
Could you please tell me what exactly do I have to set?
Thanks in advance!
Welcome to PickPlugins.
When you're editing your post grid, you can find this option under Query Post => Post Query Orderby.
Please note that to showcase the grid order Horizontally, you've to set the column count with a percentage value.
If you don't use percentage, then the grid will calculate its view Vertically.