Hahahaha nailed itSo put 2 drops in because 2 drops is enough so don't use more but if you like it stronger then you could use 3 drops but 4 drops would be too many unless you really like the scent to be heavy and travel so then use 4 drops so put 4 or 3 drops in the diffuser. But make sure you clean it out before you use it as it will be mouldy if you don't clean it out before you put your 4 drops in.
He also couldn't be bothered to plug it in, turn it on and actually show it working. Appalling effort!