Here are some additional pointers that might be helpful
LabVIEW Help : https://zone.ni.com/reference/en-XX/help/371361H-01/lvconcepts/custom_cont_ind_type/
UI Interest Group : https://forums.ni.com/t5/UI-Interest-Group/ct-p/7019?profile.language=en
LabVIEW Playlist (see NI LabVIEW UI Tips videos) : https://www.youtube.com/playlist?list=PLE91C12E1A5E62F88
I also found a blog post with pictures that show the general process for customizing controls.
If you are interested to see what is possible with LV, search for "2016 NIWeek - Designing Advanced User Interfaces in LabVIEW".