USD strength and the fraction logic
Forex Foundations
A pair is a fraction
Think of a currency pair as a fraction: the base currency is the numerator, the quote currency is the denominator. Good news for the top currency pushes the pair up. Good news for the bottom currency pushes the pair down.
Strong USD hurts USD-bottom pairs
Strong economic news for the US dollar is good for the dollar itself, but it's bad news for every pair where USD sits on the bottom, like EUR/USD or GBP/USD, since a stronger dollar buys more of the other currency.
Strong USD helps USD-top pairs
The same strong dollar data is bullish for pairs where USD sits on top, like USD/JPY, since a stronger dollar buys more yen. The direction flips entirely depending on which side of the fraction the dollar sits on.