You don't have to worry if you have complex comic organisation in the "Collection" tab, you can add groups those you frequently access to the "Favorites" tab to be able to access them quickly. Please follow these steps to do it,

1. Goto the "Collection" tab.
2. Browse to the group that you want to add to the "Favorites" tab.
3. Scroll up to the top on the screen and tap the "Add to Favorites" button.