Anyway, the problem was that suddenly after a week's use the volume on the speaker went down, a lot. Games were hardly audible at all, music and most of all ringtones and notification sounds could only be heard if you were in a otherwise silent room. I tried all sorts of settings, but all volume sliders were at max. I tried various volume changing apps, but they all stated the same - the volume was at max.
So clueless, I went to The Phonehouse (Skövde) to ask for help. They looked at it, and even called HTC to see if there were more with the same problem. Some had complained about overall low volume; and yes, the speaker volume was kind of low (not at all as loud as for example iPhone 4) from the start but you could easily hear your ringtones and the like. They had no other solution than to have me send in the phone for checkups and possibly repairs. In the store they kind of concluded that it probably was a hardware issue, since sound was good with headphones plugged in but not when using the speakers.
However, as a "last resort" before sending it in, they asked if I could try factory resetting it. I thought that it couldn't hurt but I had no hopes of it actually working. But, to my surprise, it did work. So, the problem wasn't hardware based.
I installed all my usual apps again and everything went fine. I thought that maybe I had installed some app that I had forgotten about that somehow bugged out the volume for me before the reset. Then this morning after my walk to work it happened again. Ringtones low and music (through the speaker) was barely audible.
What the frak? So I retraced my steps. What had I done between my apartment and work? I had... surfed a little, checked twitter, and been listening to the FM Radio (using the built-in app). When I arrived at work, I disconnected my headphones, picked up my phone and did the usual stuff and that's when I realized the volume was out of whack.
Then it hit me; the built-in radio app has a power button. You can, for some reason, only click it (to exit the app) when the headphones are plugged in. When they're disconnected the app tells you to plug them back in as it uses them as an antenna. I didn't think much of it at first and just clicked "home" to "close" the radio but apparently the radio was still there, in the background... So, to try out my theory that maybe you HAVE to close the radio using its own power button, I plugged in my headphones and clicked the power button, and when the app was finally closed I disconnected my headphones again.
|Built-in FM Radio app|
Voila. All volume levels back to normal. The FM Radio app had altered the volume levels behind the scenes somehow and didn't change them back until it was closed the "proper" way.
So, a TLDR...
Extremely low music, ringtone and notification volume on my HTC Desire HD's speaker.
When using the built-in FM Radio app, use its own "power" button to close the radio BEFORE disconnecting my headphones.
EDIT: I tried to recreate the problem after I wrote this post. I instantly succeeded in recreating the problem, but not the above-mentioned solution. Instead, this time I fixed it by setting it to speaker mode before (press "menu" and then "speakers") closing the "FM Radio" app and disconnecting my headphones. I'm certain that this app is the problem (for me anyway). So for me, and I recommend this for anybody else with the same problem, get another app for playing FM Radio until this issue is fixed!
Do take a look in the comments section below for more tips if my solution didn't work for you!