With for example three modules loaded, the module list will have two arrow icons at the right hand edge, with which the module icons may be scrolled left and right, starting from the sixth icon.
A click on the upper arrow moves the module list one entry towards the start of the list. The first five icon positions are fixed, shown by a somewhat thicker vertical divider between the fifth and sixth positions. The reason for keeping the first five icons statically displayed is that one may keep the most important modules always on display. You can freely choose for yourself which are the most important modules.