You can pick up to 5 icons and have up to 15 custom editors.
The configuration of a custom editor is done in Main menu > Settings > Custom Editor
First assign a name to the new editor ,(Apples p.e.)
Now fill the icon's empty boxes with your own selection of icons , like shown in the following screenshot.
Tap on Done when finished.
This editor is ready to be used in any column, let's create a new Column Add Column (top right button) .
Select your desired grade type and select the new custom editor (Apples) in Cell editor as shown below.
Now we can use the new editor in our new column!
