Confused how do I increse the multiplier?

[Johnnie Walker]

title

[Blimp]

The multiplier is highly influenced by your MPL (Maximum Primary Level). Basically try to level up your primary school higher than you have levelled your primary school in the past.

There is also a smaller bonus for levelling different schools (so try selecting different primary schools and level them)

You need to retire to get the effects of the bonus.

There's a Help panel in the game with a lot of good info!