If you are categorising your abstracts and you do not want to use the words "Topics" or "Types" for Authors to choose from, you can update the words.
For example, Category and Sub-Category, or Field of Study and Area of Expertise or even Topics and Sub-topics. To define these you can update the terminology from settings.
Follow these steps : Login >> Click on "Manage" on the Submix page >> Settings >> General Settings >> Update the text in "Allow your Topic to be called as"
