tune

To adjust (a musical instrument) so that it produces the correct pitches.

To adjust or modify (esp. a mechanical or electrical device) so that it functions optimally.

To adjust the frequency on a radio or TV set, so as to receive the desired channel.

Of faculties, senses, etc.: to adapt to or direct towards a particular target.

To make more precise, intense, or effective; to put into a proper state or disposition.

To attune; to adapt in style of music; to make harmonious.

(transitive) To give a certain tone or character to.

(obsolete) To sing with melody or harmony.

(transitive, South Africa, slang) To be impudent towards; to cheek.

(fandom slang) to adjust the parameters of singing voice synthesis software such as VOCALOID (in order to achieve certain singing techniques, increase the human quality of the voice, etc.)