Step 1 : First You need to change your size Class to wAny x hAny. Now when you open your controller all your controls will be visible as disabled, Because you change your size class and constraints defined are not compatible with it.

Step 2 : Now select all your controls in your controller then goto bottom of Attribute Inspector. You will see checkbox for C x Any. uncheck it.

Step3 : Now you have to add new Constraint for Any x Any. As you have already changed your size class to **Any x Any ** just check above check box which will by default activate constrains for current size class.

Step 4 : Then you need to add missing constraints which ever necessary for your controls.