What activities are applied to the entire system and cannot be changed after confirmation in...

 The activities that are applied to the entire system and cannot be changed after confirmation in SAP Central Business Configuration are group currency and fiscal year variant. Group currency is the currency that is used for consolidation and reporting purposes across the company. Fiscal year variant is the variant that defines the number and length of posting periods and special periods in a fiscal year. Both group currency and fiscal year variant are defined during the initial content activation and cannot be changed afterwards. Reference: [SAP Help Portal - Initial Content Activation]