IDA Help: Miscellanous Options

Editor
        A text editor is to be used when the user decides to edit an
        IDC script using the IDC tollbar.

Navigation band refresh interval (milliseconds)
        Specifies how often the navigation band will be refreshed.
        IDA tries to minimize the number of redrawings because they
        could be really time and processor consuming (imagine
        a huge program, 50-100 megabytes of code. it would
        take a long time to refresh information on the navigation
        band because the whole program will be examined to
        determine how to draw the band). If this option is set to 0,
        the navigation band is refreshed only when the cursor is
        moved far enough to reflect its movement on the band.

Convert already defined bytes
        Determines how IDA should behave when user operations
        would end up redefining some already-defined bytes

Associate .IDB file extension with IDA
        Whether or not the .IDB extension should be associated,
        at the OS-level, with IDA

Enable autocomplete in forms
        Determines whether input fields should provide an auto-complete
        combo box by default

Output files encoding
       The encoding used to generate output text files from IDA
       The value '<default>' means that the IDB's default 8 bit-per-unit
       encoding will be used.