You have some very good valid questions and concerns. Hopefully I will be able to answer/explain them for you. The reason people told you to move your speakers out of the corner is because they will sound more accurate. Your ears are accustomed to the way you have your system set-up now, and there's nothing wrong with that; it is what it is. The advice we gave you is good advice that will, technically, improve the sound. However, it may - at first - not sound "better" to you. But once your ears get adjusted to the new set-up, if you were to put it all back and listen to it again, then you would understand why we gave you the advice we did.
The reason we told you to get your speakers out of the corner is that placing a speaker in a corner will mess with the sound. A speaker works by creating sound waves. The created sound waves radiate outward and will keep moving until they hit something. If the thing they hit is hard, the sound will reflect (think of an echo). But if the surface is soft or porous, it can absorb the sound (think of trying to yell into a pillow).
When you put a speaker in a corner, the sound reflects off the walls and back into one another. The result is that the sound will become messy. Think of a gym or a pool with all of those sound waves bouncing around. Putting a speaker in a corner produces the same effect. But, there are times when you can use that to your advantage!
Putting a subwoofer in a corner is often recommended because it can improve the bass performance. So why would you put a sub in a corner and not a speaker? Soundwaves! Or rather, the size of the waves. Speakers produce smaller soundwaves than subwoofers. The smaller waves reflect closer to the speaker in the corner and into one another more quickly. But subwoofers create larger waves that reflect further out into the room and won't crash into each other the way smaller waves will.
By pulling your speakers out of the corner, you allow the soundwaves to radiate out into the room and give the waves the opportunity to create the sound the way it was meant to be heard. If your speakers are properly placed, when you play a good recording, you will actually be able to hear the guitar a little to the left, the drums in the middle, and the bass more to the right. For movies, it means that during the dog fight scenes in Top Gun, the sound of the planes will fly across the room. You may think it sounds like it does now, but if your speakers are placed better, you will notice a huge difference.
The way your main speakers are placed now, the woofers are firing right into your mattress! Most of the sound they are producing is being absorbed by all of the soft material of your bedding. That's why I suggested turning them upside down. Try it and see. Just leave the stands where they are, turn your speakers over, play some music, and see what happens to the sound.
There are 2 reasons you are not impressed with the way your system sounds when you are on your computer. First, because your bed is absorbing most of the sound. Secondly, and most importantly, your sitting on the side of your speakers! Speakers have a zone called the sweet spot. It is the location in the room where they sound the best and it is usually located directly between the speakers and the same distance away as the speakers are apart. When you sit at your desk, you are definitely NOT in the sweet spot! So your system will not sound anywhere near as good as when you are on your bed. For your situation, if you want good sound while on the computer, headphones might be a better option.
The reason people told you to move your speakers out more into the room is that if your speakers are too close together, during a movie, the sound will not be able to move. If your speakers are farther apart, when the jets fly across the screen, the sound will be able to move across your room. With your speakers close together, the sound will basically come from one location. Your concern with moving them out and pointing them straight ahead is valid. If you move them out and keep them pointed straight ahead, they will probabally not sound all that good. The secret is to turn them, or toe them in, toward your listening position. Most speaker manufacturers recommend this. If you do a search for speaker placement, both on this forum and on the net, you will find that toeing them in is highly recommended.
We all gave you good advice, it's up to you to try it. Like I said, your ears are used to the way your speakers are set-up now. Moving them around may, at first, sound different and not better, but give it some time. Experiment. Toe your speakers in a little and listen, then toe them in a little more and listen again. Raise them up, turn them upside down, or even on their sides. Have fun! One thing I've found very helpful for aiming my speakers is one of those laser pointers. I just hold it on the inside edge of my speaker and I can see exactly where my speaker is pointed.
Just try some of the things we have suggested here and see if it improves anything.