How to Add Currency Symbol Automatically in Excel 

How to Insert Country Name and Currency Symbol AUTOMATIC in MS Excel: Format numbers as currency
If you want to display numbers as monetary values, you must format those numbers as currency. To do this, you apply either the Currency or Accounting number format to the cells that you want to format. The number formatting options are available on the Home tab, in the Number group.
Format numbers as currency
You can display a number with the default currency symbol by selecting the cell or range of cells, and then clicking Accounting Number Format Accounting number format button in the Number group on the Home tab. (If you want to apply the Currency format instead, select the cells, and press Ctrl+Shift+$.)
If you want more control over either format, or you want to change other aspects of formatting for your selection, you can follow these steps.
Select the cells you want to format
On the Home tab, click the Dialog Box Launcher next to Number.
Tip: You can also press Ctrl+1 to open the Format Cells dialog box.