Can't arrange the icons on my Macbook the way I want!

After a recent update, I can't arrange my icons on my desktop the way I want ... they are locked in a grid instead of floating freely where I put them. Sometimes I group several overlapping temporarily, or groups in one corner area, or put specific icons in specific places ... but now they lock in a grid and I can't find a "preference" that changes that setting.

How do I arrange my own desktop the way I want?

Thanks, Gary