We can change the account from GUI . Follow the below steps to achieve this.
1.Please make a note of the request id’s you want to change.
2.Choose All accounts from the account drop down on top.
3.Select the request id’s by selecting the check box to the left side of the request.
4.Click on edit request.
5.Click on site drop down.
6.You can find the sites listed followed by the account name.
7.Choose the site belongs to the account to which you want to move the requests.
Note:Please try this with any one of your requests and then go for the bulk edit.