You could edit your existing time dimension or create a new one and promote your date dim with the new time dimension.
To edit the existing time dimension, You would have to Open Time dimension panel for an existing time dimension (right click on the time dimension and edit), (you could create a new Time dimension, if you don’t want to make changes to the existing Time dimension)
Under the Formatting section, select year or month or week or day and format each level (if you’d like just so that you have the date appearing as dd/mm/yy etc and not just end at week level), you can check under preview option how the date appears at a specific level.
Additionally, you could refer to this support article on Formatting time dimension levels.
Once you’ve made the changes to the time dimension, you need to demote the existing date dimension and promote it again using the updated or a Time Dimension at cube level , so it takes the format you just set. It’s similar to promoting a dimension with a hierarchy.
After you assign the hierarchy at the cube level, your date filter should be updated with the new format and not just end at the week level.
Please let me know if that works for you or if you’d like to discuss this issue over a call.