Question

Who has changed the the consumer surplus as buyer surplus?

Answer 1

When there is a difference between the price that you pay in the market and the value that you place on the product, then the concept of consumer surplus becomes a useful one to look at. This is an important idea that you can use on many occasions in your exams.
 Consumer surplus and economic welfare 
Consumer surplus is a measure of the welfare that people gain from consuming goods and services 
Consumer surplus is defined as the difference between the total amount that consumers are willing and able to pay for a good or service (indicated by the demand curve) and the total amount that they actually do pay (i.e. the market price).
Consumer surplus is shown by the area under the demand curve and above the price.

Answer 2

Explanation:

A bank mediates between those who have surplus money and those who need money by allowing both to open accounts with it. Banks only keep about 15% of cash reserves to provide to people who come to withdraw money on a daily basis. Those with surplus money are encouraged to invest with the bank and are paid a certain rate of interest for the same. Those who need loans are required to pay an interest on their loans. The difference between payment to lenders and receipt from borrowers comprises the bank’s earnings. Thus, the bank acts as a beneficiary for those with surplus money as well as those who need money.