Hi @Enric_Moreno Thank you for reaching out!
Apologies for the confusion. What you are doing is correct. Let me give you some context here.
By default, tasks that are first assigned to you are placed in the Recently assigned section. From there, you have the option to manually place them into the Today, Upcoming and Later Sections according to your own organization.
The ability to Mark tasks as Today, Upcoming, or Later is for your personal prioritization, and is only relevant in the My Tasks list. This means that these sections are not inherently connected to due dates, so unless you prioritize your tasks between these sections, they will by default remain in the Recently Assigned Section.
You can learn more about My Tasks in this Guide Article: https://asana.com/guide/help/fundamentals/my-tasks#gl-priority
I hope this helps clarifying but please let me know if you have any follow-up question! Have a nice day!