I'm having a lot of trouble hitting the 3rd not 4th octave C. Each time I try to play it, it cracks and its played out very loud. I can play all the notes around it softly and without any problems. Is this a problematic note for some flautists?

The third octave generally is difficult to play in tune and quietly. Be sure to use a very focused and directed airstream, rather than just forcing as much air as possible into the flute, check your fingering, and keep the air pressure up. Slur from high B to the C above it and hold that C out to get a feel for where it is. Don't be afraid to play it loud for now, and gradually learn to control it better.

Ok. Thanks. I'll try that tomorrow when I practice.

Try bending the note as well, make it sharp and flat as much as you can without losing the note. It's hard, but it takes practice.

Some advice: Wear earplugs

sometimes when you think about a note you dont like very much whilst your playing it, you make your lips go tense without realising it - i do this quite a lot with top f#. Just try and relax when you play it!

Thanks for all the input everyone. I think I actually scared of the C because I could never play a few years ago.