This is done in calibre itself, rather than in CC. Configure this by going to calibre's preferences, then "Sharing over the net". There's a box towards the middle called "Max ungrouped items", which defaults to 100. That means that it will only group by first letters once there are more than 100 items in a particular group. You can set it to a lower value, with a minimum of 25. This will then use grouping by first letter in most things other than sorting by title or by newest.