Question:

Why it is not possible to schedule a Call on the weekend days?

When using the Schedule a Call button on the My Accounts page, Calls are automatically saved on the next Monday when they are scheduled for Saturday or Sunday.

Answer:

This is expected functionality. Calls cannot be scheduled for non-business days with the Schedule a Call button. It is controlled by the locale of the user.

Example: if in an Arabic locale, save the Call on Sunday.

Related Documentation:

CRM Help Documentation: Accounts Overview