I am curious as to where you obtained your screenshot.
It does not look like that of 2018, When I check the categories I have three buttons on top as shown below. Yours only shows the View Types button and not the Resources Manager and File Locations.
My brushes from 2018 include the categories - All, Artistic, Brushes. Media Brushes and Stamps and no trees .
So will assume you have imported or created your trees and placed them in the Tree Brushes category folder.
I will go through the steps to create a category called Spooky Trees
The folder and brushes will go into this location
C:\Users\*username*\Documents\Corel PaintShop Pro\2018\Brushes
Each compatible brush consists of two files eg
BrushTip_ekrspookytree 001.PspScript
ekrspookytree 001.PspBrush
1. I used windows explorer and navigated to the Brushes folder mentioned above ...2018\Brushes , and set up a new folder Spooky Trees
2. Opened Spooky Trees and then copied the two files for one brush mentioned above.
3. Started PSP 2018 , set up a blank document and chose the Brush tool. Clicked the down arrow and observed that my Spooky Trees folder category was there and it contained only one tree which was the only one I had copied to that folder..
4. Closed PSP 2018 and then copied the rest of the spooky trees into that folder ( I had downloaded them from a PSP Brushes site so they were all in the compatible form and did not need to be Imported as one does with Photoshop Brushes.)
5. Opened PSP 2018 as in 3 and there were all my 15 spooky tree brushes.
This procedure can be done for any category you like and any number of brushes.
You can of course use the Resources manager if your brushes are already there by selecting those brushes then Move then navigating to the Brushes folder in your ...2018\Brushes and then creating a new folder and naming that . The files are then moved from the main part of Brushes into that folder. More complex that way - I prefer to just do the rearranging while PSP is closed from Windows Explorer.
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