SuperMemo tab in Tools : Options provides the following options:

• Narrow captions - use narrower captions that take less desktop space and allow of longer texts. With this option on you need to minimize narrow-caption windows using Minimize on the the system menu. You can open the system menu with Alt+space or right-click over the caption
• Trim shortcuts - turn off a couple of 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 www.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. Use this option if you have a permanent connection to the Internet
  • Optimize - (default option) use CHM help if it is not too old or HTML help if it is not outdated, or connect with the Internet if both local help systems are outdated
• Interface font - define the font used in windows and dialog boxes throughout SuperMemo. If you select a very large font SuperMemo will ignore your choice so that at least you were able to read the dialogs and change your setting back
• Default font - default font use in templates that do not use any registry font. Changing this font here will change the font displayed in all elements that use the default font. When you first choose Add new before defining any templates, SuperMemo uses the default font
• 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 pop-up 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 Algorithm-SM8 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)