How do you set a (Primary Category)

How do you set a (Primary Category)?
https://forum.flynax.com/attachment....tid=4297&stc=1

https://forum.flynax.com/attachment....tid=4298&stc=1

1. Go to Categories > Categories > Add a Category
This is the Category you want to act as your Primary Category
This Category might already be created
Leave "Listing Type" blank for now

2. Go to Listings > Listing Types > Select / Create a Listing Type > Edit > Category Settings > Primary Category > Select Category Created Above > Save

3. Go to Categories > Categories > Select Category from Step 1 > Edit > Listing Type > Select "Listing Type" in Step 2 > Save

4. Go back to Categories > Categories > Select Category from Step 1 > Build > Build Listing Form > Add Listing Fields to Form > Save

5. Go back to Categories > Categories > Add a Category > Create More Categories with the same "Listing Type" as Step 2
All of these additional categories must NOT have any Listing Fields.

6. Go to the frontend and log in as a user.
All categories you created in Step 5 will have the same Listing Fields as the Primary Category in Step 4

I hope I got that right.
If not, I will edit