Place the brown sugar in a microwave-safe bowl with a damp paper towel on top; microwave 10–20 seconds, check, and repeat until soft
Put brown sugar in a sealed container with a slice of fresh bread; leave overnight, then remove and re-seal
Store brown sugar in a sealed container with a damp paper towel; check after a few hours, then re-seal
Use a sealed container with a damp (not dripping) towel or cloth; soften over several hours or overnight
Break up sugar, then microwave in short bursts with periodic stirring and a damp paper towel
If very hard, bake in a low oven (around 250°F / 120°C) in a covered dish for 5–10 minutes, then stir and cool briefly before using
Avoid adding water directly to the sugar; add moisture via a damp towel only
If it becomes too soft, spread it out to dry slightly before storing again