SuperMemo tab in Tools : Options provides the following options:

• Remove hidden formatting - remove formatting from formatted texts that are used only as unformatted texts. For examples, if a formatted text is used only as an element title, its formatting is redundant and takes additional space. SuperMemo can remove this formatting when you execute File : Repair collection. If you use a formatted text in a plain text component, this formatting is invisible and will be removed as well. However, if you would like to later change your template to rich text, you will only be able to view the plain text  
• HTML status border - show borders around HTML components to indicate full HTML, outer HTML and plain text
• Trim shortcuts - turn off Alt+Del shortcuts that make it difficult to get diacritical characters in some national versions of Windows. Keep Trim shortcuts unchecked if you are using English Windows or you do not experience any conflicts with keyboard shortcuts
• Help system
  • Microsoft Help (CHM) - always use smhelp.chm help file located in the bin subfolder (if installed). You can download this file from here
  • HTML Help - always use HTML help files located in the help subfolder (if installed). If you copy the entire SuperMemo website from supermemo.com to this subfolder, SuperMemo can use it for context-dependent help
  • Internet Help - always connect with the most recent version of help on SuperMemo website (located at supermemo.com/help)
  • Optimize - (default option) use CHM help if it is not too old or HTML help if it is not outdated, or connect with the Internet if both local help systems are outdated
• Default background image - define an image displayed by default in the background of all elements in the element window. For that purpose type in the name of a selected image registry member. To add an image to the registry, choose Search : Images : Import files beforehand. Default background image is always tiled. If you would like to add individual backgrounds to particular elements or choose a given display mode, e.g. center, stretch, tile, etc. use Background options on the element menu (Alt+F10 in the element window)
• Children limit per branch - for performance reasons, SuperMemo makes it possible to limit the number of elements that can be children of a single element in the contents window. If you keep this number in the range 20-100, you can be sure your collection is easy to review and browsing it is significantly faster than for larger tree nodes
• Plug-In Algorithm - install an external repetition spacing algorithm shipped as a plug-in DLL (see: Neural Network SuperMemo). To replace the standard SuperMemo Algorithm with a plug-in DLL, choose Install and pick the DLL. To restore the default state, choose Restore default. Please note that you should install your plug-in before you begin the learning process. You cannot switch the algorithm after repetitions have begun without resetting your collection. Plug-in algorithm is assigned to a given collection, not to SuperMemo in general. This way you can make repetitions in different collections using different algorithms (including your own algorithm as long as you can write your own DLL)