SQL update for the varchar column

I want to change the string of AttachmentCopyLoc columns from D:\IT\Public\FTX_RobotAlerts\336 to V:\IT\Public\FTX_RobotAlerts\336 only change here is D to V, the remaining string is the same (I don't event want to change that).

How can I do that?

Thanks in advance for your help.