How does validation work in Proof of Stake?

I understand that in PoS there is no mining, but rather there is validators, who are selected at random, with chances varying proportionally to the size of their stake.

The validator gets chosen at random, they validate the transactions, then these transaction gets verified by other nodes to make sure it's not fraudulent, and the original validator gets a reward. UNTIL HERE all makes sense.

Now, how does the validation process look from a first person POV when you are staking for a cryptocurrency. Do you stake your coins, and then your computer takes care of the rest? - or do you have to manually validate transactions if you get selected? - I've always assumed it's automatic, but because videos usually touch on the risk of validators approving fraudulent transactions, I'm led to believe there must be a way to do this manually (?)

TL;DR - If anyone could explain how the validation process looks from a first person POV from the validator's perspective, I would greatly appreciate it.