Struggling to understand percentages

Man oh man. I have been struggling so much with math for work. Percentages to be exact. I don't understand them very well.

I keep running into the same problem, I try to google it, I get even more confused.

If I have something that's 8 inches and I need the item to be 10 inches, how much of an increase is that?

My brain wants to say 20%, google said it was 25%, but my printer says "25% is shrinking it". H u h????

I'm so frustrated and upset. I want to learn this so I can fix it. The amount of times I've messed up at work because of this is unreal. Does anyone know what grade teaches about percentages? My parent used to preach how important math was but when it came to teaching me, they didn't have what it took. It never made a lick of sense until I saw physics. However I've only barely seen physics so it's still confusing to me. Oh but I adore physics so much, it makes math so much less confusing. It's like visually seeing math move and it makes so much more sense.

I'm really good at simple mathematics like addition and subtraction. But percentages, fractions, and decimals? Im very bad at it.