i started playing the oboe less than a month ago- i switched from flute. i can get the low notes on it really easily but high A B and C sound pathetic and flat. how can i sort this?

I used to have a problem with playing those notes too. Are you making sure that you press the side key when fingering the notes? If you are, then you might want to try a different reed strength and making sure that the reed is thoroughly soaked.

Ill give you this hint. When ur playing low notes dont use much firmness on the reed but the higher the notes go increase the firmness on the reed. It could also be u need a new reed, need to get ur oboe repaired, or u have a selmer.

Yeah, make sure you hit that side key or you will be blowing a lot harder to get that note to come out, same with the firmness. At first when I got those notes I ran out of breath quickly, so remember to apply the air pressure.

It may be asking too much of your embouchure to get A, B, and C above the staff just a month after picking up the oboe. Those notes are often out of tune anyway even for experienced players, and whether beginner or professional, those notes require a stronger embouchure. In other words, it may be best (if possible) to steer clear of those notes for at least another month or so. Develop your technique and mouth muscles in the lower registers--you have plenty of time to move to the higher notes.

As a side note, though, higher notes often sound easier if you put more of the reed into your mouth. My oboe professor swears by pushing almost the entire reed into his mouth, almost down to the threads. It works well for both of us and doesn`t seem to compromise the tone in any way.

Okay, the fingerings for flute are similar to the ones for oboe, so that should somewhat an easy task. Getting the high notes on the oboe takes great breath.
Most beginners `cheat` by pinching the reed, this way the reed is firm, but myself personally, don`t pinch.
My director tells me to open my mouth, while keeping your lips on the reed. Support your stomach! Supporting your stomach will keep the air steady, and getting the high notes out requires good air control. Suck in your stomach as you are blowing into the instrument. Keep it that way.
Another technique is as posted already, to `eat` the reed. No, don`t chew on the reed, but put your lips all the way to the thread and BLOW! My tutor taught me this technique because I was doing All-Region and had to get this high E out. Of course, it was difficult at first, but I got it out.
When I was a beginner, I couldn`t get the high notes out either. Happens all the time. But over time and this year (My Symphonic year.), I learned to support my stomach and that really helped! If you need any additional help with the oboe or anything else, feel free to contact me.