(Android)
To activate collections on the Android version of the app, you can go to the gear under the collections list item at the three dots of each word. This will open the advanced collections menu. Here you can assign the available slots by entering a name for your collection and, if necessary, activate the slider next to it to display the collection in Quick Access.
(IOS)
To activate collections in IOS, you can do so from the Collection tab. There is an Edit button at the top of the tab that opens all collections. You can then enter the desired collection name.
To display them in the quick access, you have to go to the settings and under Collections you can activate the slider for the respective collection.
In both versions it is possible to add a word to several collections. This specific word will then be displayed in all collections to which it is assigned.
Quick Access collections appear on the first page of the Word menu, while other collections appear only in the submenu.