After importing the Categories.json file into your own Parse Dashboard, you have to double-click in the empty space between the edge of a cell and the blue image button to replace the existing images, check the screenshot below:

That may happen sometimes, it’s a bug in the Parse Dashboard, so in this case you must manually add rows and columns on your own.
1. Click Edit -> Add a column, choose String as type of data and type exactly category, then click ‘Add column’
2. Click Edit -> Add a column, choose File as type of data and type exactly image, then click ‘Add column’
3. Now you can enter the empty cells and insert the name of your first Category, doublie click in the empty cell of the image column and upload your first image.
4. Repeat the steps above for each category you want to insert in your Parse database.

The only way to do that is to remove all rows into the Categories class and add then again based on the order you want categories to be shown in the Home screen of the app, since they get ordered by their ‘createdAt’ date.