Enharmonic defaults

Just now I input some notes with my Midi-keyboard. The piece has two sharps (D major). The notes input all have flat symbols. Some questions:
a. why isn't the enharmonic default on the sharp notes altered into their flat counterparts;
b. why isn't it possible to do the Enharmonic spelling on a group of notes instead of one-by-one;
c. why can't I apply the Enharmonic at once on an octave (both notes alter at the same time);
d. why is the scope of an accidental (2,3 or 4) beyond the note you input and stretches its influence to all subsequent notes and why doesn't it follow the enharmonic default given by the flats/sharps at the beginning of the piece/system. It is a bit silly to input a sharped f in a piece in D major while there is no need to (e.g. no flattened value before);
Raymond
a. why isn't the enharmonic default on the sharp notes altered into their flat counterparts;
b. why isn't it possible to do the Enharmonic spelling on a group of notes instead of one-by-one;
c. why can't I apply the Enharmonic at once on an octave (both notes alter at the same time);
d. why is the scope of an accidental (2,3 or 4) beyond the note you input and stretches its influence to all subsequent notes and why doesn't it follow the enharmonic default given by the flats/sharps at the beginning of the piece/system. It is a bit silly to input a sharped f in a piece in D major while there is no need to (e.g. no flattened value before);
Raymond