You want to change the order that items are displayed on the Top Navigation dropdown in the top left of the BizX screen.
SAP SuccessFactors BizX Platform
It is not possible to change the order of items on the Top Navigation dropdown.
The order is pre-determined and the items created through Custom Navigate are shown at the end of the list.
Drop-down modules list , KBA , LOD-SF-PLT-NAV , Custom Navigation , LOD-SF-PLT , Platform Foundational Capabilities , How To