Advance Corner で なく Advance Ticket Window です

7かいまでスタヂアムのなかで ticket upgrade ができるならしあいのまえ そとの ticket booth でも できるとおもうけど くわしくは でんわできいたらいいとおもいます。

from http://newyork.yankees.mlb.com/nyy/ballpark/guide.jsp#u

UPGRADES
Until the end of the seventh inning on game days ONLY, fans looking to upgrade or change their seat location may inquire at Yankee Stadium Advance Ticket Windows located inside the Stadium on the Field Level at Sec. 9 and 20 and in the Bleachers at Sec. 43. All upgrades are subject to availability.

In the event that an upgrade is available and the new ticket(s) value is GREATER than the original ticket(s) being presented for upgrade, the difference in price must be paid by CASH ONLY. No other form of payment can be accepted for a ticket upgrade.

In the event that a change in seat location results in the new ticket(s) having a value that is LESS than the original ticket(s) being presented for upgrade, the difference in price will be issued back to the ticket holder in the form of Bomber Bucks (Gift Certificates). No CASH or other forms of refund will be provided back to the ticket holder.

Yankees Season Ticket Account Holders Get complete information about your account, including tracking information, FAQs, and more in our Season Ticket Holder section. Click here to access this information.