Hi and welcome to the Forum!
Sound volume does vary a lot across apps and YouTube videos. But are you saying it was once louder and not anymore. Good idea to maybe close the app you're using completely and then relaunch it. From the home screen do the four finger swipe up or double press the home button to reveal your multi task bar. These are all the apps that you have opened at one time. Long press the app until it jiggles and a red minus sign will appear above it. Press the minus sign, this will close the app, not delete it, now press the home button to return to your screen. It's also a good idea to close all these apps, as it helps the iPad run smoothly.
A restart occasionally is also a good idea, Press and hold the power off button, the one at the top right. You will see a slide appear to power off, slide this and the screen will go dark and a Whirly will appear. When the Whirly disappears your iPad is now off. Press the power button again until the Apple logo appears, this will take a few seconds and your iPad will restart. You should restart your iPad occasionally also as it will keep it running well. Now see if sound is now better.
The IPad Forum is a community of members from all walks of life and from all over the world coming together to share our experiences and to help each other learn about this wonderful piece of technology the Ipad. There is a wealth of information already here in the many threads we have so doing some searches will answer most of the questions you have. If then you cannot find the answer you are seeking then by all means post your question. There are many friendly and informed members here only too willing to help you.
We also have our own App - It is a very simple app to navigate.
http://itunes.apple.com/us/app/discussion-forum-for-ipad/id412896524?mt=8
Reading the IPad manual is a great place to start so please download a copy of these.
http://www.support.apple.com/manuals/ipad/
2 very informative threads from which you will learn many tips and shortcuts for the IPad.
http://www.ipadforums.net/ipad-general-discussions/21590-tips-tricks-those-us-who-dont-know.html
http://www.ipadforums.net/ipad-os/49581-ios5-tips-tricks.html
We have rules like any Community so please read these also
http://www.ipadforums.net/forum-rul...um-rules-everybody-please-read.html#post14697
Once again we welcome you here and are so pleased you have joined us!