How to make additional subcategory 4+

How to make additional subcategory 4+

Hey there, 
just wonder how to make additional category 4+ for incidents? 
I found that system limits the sub's on 3rd... 

My idea is to creare this subcategories that i couldn't do.

Hardware,Print,Label Printer,Incident,Can't connect
Hardware,Print,Label Printer,Incident,Can't print
Hardware,Print,Label Printer,Incident,Error Code
Hardware,Print,Label Printer,Incident,Needs Category
Hardware,Print,Label Printer,Incident,Paper Jam

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