It requires another step to find the account number. You must open the account to see it. The account number is the one thing that is UNIQUE and it is shown when the name is found. If I am searching a list of names, say 50 to 100, to confirm they are or are not in the database and I want the Account Number of the ones that are, it is necessary to "Open Each Account" to find the number.
When you are on the Find Account page, you can choose which columns you see, by clicking the "Choose columns" button. From that list you can choose a variety of different fields including Account Number. Once you have done that, the account number will show up each time you go to find an account. BONUS: You can also just click and drag those columns in any order you want, so if you want the account number to be the first column, you can customize it to be that way.