First, you need to ensure that the company file is set up for multiple currencies.  Do this under Settings/Company/Currency and check off the box for "I want to enter transactions using Foreign Currencies."  Then, create a GL account for the US Bank and ensure that the account class is set to "Bank" and that the currency is set up to USD on the "Class Options" tab.  When you are setting up the customer's information, you will need to select the correct currency on the "Options" tab.  You will need to set up a customer twice (one for CAD and one for USD) if you invoice them in both currencies. When you are receiving payments, you should be able to select either account for the deposit before posting the transaction. 

Open up the Sample Company in Sage and from help search the terms Foreign Currency. Below is from the help file and also will give you ideas what to do and search on for more detailed information.

Turn On Foreign Currency Transactions

Related topics

Add or modify a foreign currency

Set up reminder to update a foreign currency

Update the exchange rate for a foreign currency

Learn about using foreign currencies

Before you can perform this task

Switch to single-user mode (Sage 50 Premium Accounting)

To set up foreign currencies in your company:

1. In the Home window, on the Setup menu, choose Settings.
2. On the left side of the window, click Company and then Currency.
3. In the Home Currency section, enter the settings for your home currency.
4. Select the Allow Transactions in a Foreign Currency option.
5. Select an expense account to Track Exchange and Rounding Differences.
6. Click OK.

Why is it in my company file which I have just created after installing, the Currency section check box for allowing foreign currency is dimmed out and also the Home currency which is showing CAD is dimmed and not allowing me to check mark the box and selecting to allow foreign currencies

Are you logged in as sysadmin, in single-user mode and have all other windows/dialogs/data entry screens closed?

I have just installed and open the application. I have not set up users. So if I open the app does it not mean I am automatically in the app as admin?

Yes, it sounds like you would be logged in as sysadmin.  To confirm, what name is showing at the bottom right-hand corner of the Sage 50 Home Screen?  It will be to the left of the envelope and if you are using Premium or higher, it should say Single-user or Multi-user also.

If you are using Pro, I can't remember if Single-user shows or not.  However, if you are using Pro or are in single-user mode, and the name says sysadmin at the bottom right, then your issue is likely open windows.  So click on the Close other windows button at the far right on the toolbar and try going to Setup, Settings, Company, Currency again.

To make sure all other windows are closed go to View > Close all other Sage 50 Windows

To set up a US bank, heads that there's a lot of steps... you'll first have to create a Realized Exchange Gain/Loss Account, to do this:

1.  Go to the Company module > Chart of Accounts and View Accounts
2. Scroll down to the General & Administrative Expenses group (5600 #s), add the realized exchance gain / loss account in this group.
3. Click File > Create
4. Enter the account number you want (ex. 5750) and add description: Realized Exchange Gain/Loss
5. The Account Type should be Group Account
   
6. Select the Class Options tab
7. In account class downdown menu select Loss
8. Click Save > Close

Next, when you go to Settings > Company > Currency, you should see the below, note the bottom corner login of sysadmin. Activate the option I want to enter transactions using Foreign Currencies. The home currency in CAD is auto selected.

Once activated, in the field Track Exchange and Rounding Differences, select the gain / loss account created above. Then under Foreign Currency select USD. The Code and other fields auto populate.

Click Exchange Rate to start configuring exchance rates. Activate the option to Display a reminder if the exchance rate is xx old and select One Day in the drop-down menu. In the Currency Exchance Web Site field, enter www.bankofcanada.ca/rates/exchange. Then in the table, select the date and enter the rate for the day. Click OK twice and return to the currency settings to save your changes.

After the above screen closes, on the Options tab, change the Currency to USD.

On the Taxes tab, change the default tax code to No Tax, then Save and Close

Finally, to add a Foreign Currency Bank Account, go to the Company module > click Chart of Accounts >View Accounts. Find the subgroup in the Current Assets group (1000's). This group is where you'll add the currency bank account. Click File and select Create. Enter:
- Account Number (ex 1060) and Description: US Bank Account
- Account Type: Subgroup Account

On the Class Options tab, enter:
-Account Class: Bank
-Transit #, the Account #
- Currency: USD
- Account Type: Chequing

Then save and close

From the Setup menu, select Settings, then expand Payables and select Linked Accounts.
For the USD currency, select the account created above (ex. 1060-US Bank Account for us).

Expand Receivables and select Linked Accounts. For the USD Currency, select the account (ex. 1060-US Bank Account). Click OK to save your changes.

Hope this helps clarify things for you and others!
Erzsi