Q: iPhone 6plus water damage makes the display not hd anymore

Hi, so a few months ago I dropped my phone in a pond while fishing (it's the 6plus) and I immediately took it out and laid it in the sun to dry after a while I cracked and had to see if it was working, the screen was working but the sound was not and the finger scanner was not and the home button was acting strange, anyway when I got home that night I put it in rice for two days and when i took it out to my surprise everything was working fine except the screen, it had water lines and spots all over it, i read on here that if you put your brightness up all the way and fully submerge it in rice with the charger in it would be fine again, so the next morning after I did that I noticed the display looked a bit strange, the problem is the screen isn't hd anymore, I don't know a better way to describe it has the display of a first generation iPad when it's supposed to be the best there is plus the water lines and spots didn't go away but now they only come out when there's a black screen or i turn my brightness down, I've been searching the web for three months looking for someone in the same predicament as me and I can't find anything and I'm so frustrated please help!!