How to easy change layout in existing records in Deals?

How to easy change layout in existing records in Deals?

Hello,

So far i have used only 1 layout in Deals. I have about 1000 records. Now i want to make new layout. So i have 2 layouts:
Layout Old (1000 records)
Layout New (0 records)

How to easy change layout from Layout Old into Layout New for existing records? I have about 200 records to change layout.

Could you advise me?