you know, people DO 'see' words differently...some actually visualize the page on which the words were printed when they learned them...others 'feel' the basic auditory memories...some can only remember 'story' songs where one verse leads to another......If you can identify the songs you do remeber ok, and ask yourself exactly what is is you are 'seeing' as you sing, maybe you can refine that technique.

I know one well-known Mudcatter who simply sets up a music stand at a concert...and then proceeds to sing wonderfully!...I often need a crib sheet for songs I have not done a lot...(but often, just having the sheet available allows me to relax and sing it)

I saw Norman Kennedy last weekend for 4 hours of singing, and he USUALLY closed his eyes..(so as not to be distracted?)...but he also muffed a few lines on occasion and went thru some arcane process to recover them...

it is just not the same for everyone...