parameterOverrides

A list of input parameters whose values you want to update for the specified stack instances.

Any overridden parameter values will be applied to all stack instances in the specified accounts and Amazon Web Services Regions. When specifying parameters and their values, be aware of how CloudFormation sets parameter values during stack instance update operations:

• To override the current value for a parameter, include the parameter and specify its value.

• To leave an overridden parameter set to its present value, include the parameter and specify UsePreviousValue as true. (You can't specify both a value and set UsePreviousValue to true.)

• To set an overridden parameter back to the value specified in the stack set, specify a parameter list but don't include the parameter in the list.

• To leave all parameters set to their present values, don't specify this property at all.

During stack set updates, any parameter values overridden for a stack instance aren't updated, but retain their overridden value.

You can only override the parameter values that are specified in the stack set; to add or delete a parameter itself, use UpdateStackSet to update the stack set template. If you add a parameter to a template, before you can override the parameter value specified in the stack set you must first use UpdateStackSet to update all stack instances with the updated template and parameter value specified in the stack set. Once a stack instance has been updated with the new parameter, you can then override the parameter value using UpdateStackInstances.