Tools : Options on the main menu opens the options dialog that makes it possible to customize SuperMemo and the learning process. You can open this dialog in levels below the middle level with Alt+O (i.e. even if the Tools option is not available on the main menu).

Options dialog includes the following tabs:

SuperMemo: Tools : Options : Learning tab

Global options of SuperMemo are stored in the file supermemo.ini in the SuperMemo subfolder BIN.
Options that affect only the current collection are stored in the file collection.ini in the collection subfolder (named in the same way as the collection). Tools : Options will modify both these files and change relevant settings