How to fix this on minecraft?

Ok so when ever I punch the trees and collect wood I make that into the planks but after that when I drag my planks to the crafting menu to make a crafting box, it picks up the whole stack and puts it into one box, and I can't figure out how to put just 1 plank, instead of the whole stack so I can move on and make my crafting table and start my mine. (I have it on my mac btw I just got it I've been playing on the iphone which was way simpler)

Don't left click, right click.

While the block is in your inventory:
Left Click with your cursor = Pick up all blocks
Right Click with your cursor = Splits the blocks

While you have blocks selected with your cursor and want to put it in a chest/ work bench slot:
Left Click puts all of the block on the slot you're cursor is hovering over
Right Click puts one of the block on the slot you're hovering over
Hold Right Click + Drag = Puts blocks in the slots you dragged over with your cursor.

Hopefully this makes sense but you'll get the hang of it.