1) I tried the palming and tried to remember the letter and when i looked i saw it perfectly for 5 secs. How do i hold on to it and get perfect vision
2) everytime i yawn i get perfect vision for 5 secs and i want to know how to improve my vision
3) everytime i blink softly i get perfect vision for a couple of seconds and i want to know how to improve my vision to make it perfect
4) everytime i look at the sun directly i get perfect vision for like 8 secs and i want to know how to improve my vision to make it perfect

So just practice these methods as much as you can. Esp. number 1.
Before the end of 5 seconds (before you lose the clear vision) quickly close your eyes and palm some more. Do this for as long as you can, if you can do it for an hour or hours a day, you will be sure to succeed. Also, read the Bates book if you need more tips and/or want to understand more. But if you just get one technique working, you can already succeed. I can see you are quite impatient, so there is no need to know and understand everything and waste your time, if you just practice what already works and spend time with it...