I was trying to tighten my front shifter (the cable felt loose) and now I regret I did it. I messed it all up and it wouldn't shift into any gears. Then, I read how to use high and low front derailer screws to adjust gears. I got that to work, but now the shifter keeps downshifting by itself. It takes a lot of preassure to upshift, but almost none to downshift. So much that it downshifts by itself. How do I adjust it?
What type of shifter do you have.
It sounds like you have an indexed system and the index is set in the wrong place, which means that the cable tension is wrong.