I want to look at all my tasks for the day an prioritize them.
you can do this in two ways:
1. By clicking the "today" link below the search box and then editing each task displayed in the "today" section to add !p1 - !p4 or using the gear icon on the right side and choosing the priority level.
2. By accessing a particular project and sorting it either by date or by priority (form the "Task actions" gear icon at the top right of the list.
Please note that in the "today" view, tasks are sorted primarily by date/time and secondarily by priority. If you have many tasks scheduled for one day and 4 priorities are not enough, you can use fixed times (like "tomorrow @ 16:00" instead of simply "tomorrow") which will result in an exact sort of the "today" list by due times.