How can I get a buzzer to sound louder? The little buzzer that came with a beginners kit sounds barely above a whisper.
Either get a bigger buzzer or mount the one you have on something like a shoe box.
Is there a sticker on it? Are you using it correctly?
Assuming it's a transducer (like a speaker where you feed it the frequency/signal), make sure you are using a high-enough frequency (maybe 2-5kHz). Those things don't reproduce bass.
And if you have a buzzer/beeper (with a built-in tone generator) connect it to 5VDC (don't use the tone() function).
It's difficult to know without seeing a picture. But I have an old electronics starter kit with a buzzer hanging around somewhere, from what I recall that one just needed 5v DC and produced a quite loud buzz - probably around 60dB or a bit more.
It may be worth checking it's resistance before connecting to an Arduino output, just in case it's based on a speaker. Make sure the output doesn't see less than 200R without buffering for more power.