Record Update Issue in SQL

Hello,

I have thousands of records in SQL database and one column is there with the name "Address" which contains the values like "'L12 West St" or "S12 East St".

Here , i want to update the character "St" to "Street".

When i am trying to do this, it is also updating "East" to "EaStreet". or "West" to "WeStreet"

But i want to update only character "St" to "Street".

How i can do this ?

 please respond me.

Thanks!!!