How do you change your pitch in a song?
Um.. no offense, but if you don't know the fundamentals of singing, you're probably not a good singer (yet). level and pitch are two completely different things. level translates to volume, pitch is the note you're singing. find an audio recording of a chromatic scale, such as the popular Do Re Mi Fa So La Ti Do in C major perhaps. Try to replicate those notes. sing from your stomach.
How do you change your pitch in a song?
You need to find out if your friends are talking about volume or pitch, two different things. Volume is generally about quietness and loudness but the character of a voice also changes as a person sings at different volumes. Janis Joplin didn't just raise the volume of her voice so she is louder, she did it to get a certain raw character to her voice that reflects the blues/soul/rock that she performed.
Pitch is about the note you are singing, there are 12 notes in western music; C, C#, D, D#, E, F, F#, G, G#, A, A#, B and back to C (making it 13 notes from octave to octave). If you are singing a note that is relevant to the key the song is played in then your pitch is fine, but sometimes it is appropriate to change from one note to another even if the instruments don't, the voice can be treated like an instrument, and a bassist can stick to one note over a number of bars while the guitar carries out a solo of multiple notes, the voice can do the same, the band can be playing the same note or chord while the voice changes over the top of everything else (aslong as you stick to the key).
