You can access the Sources screen from within the Information Tab of the Dataset screen, or by going to the Data drop-down menu and selecting Sources.
To add a source, click on the Add New Source button. This will take you through a set of instructions on how to add the source.
You can Edit an existing source by clicking the Edit icon in the bottom right hand of the source:
You can Delete a source by clicking the Delete icon in the bottom right hand of the source. Note that you cannot delete a source if it is in use within the file.
An excel source contains a Name to help identify different excel sources. You would use a different excel source for different charts of accounts imported via excel.
For example, suppose you have a client who has two stores who use MYOB v19 (but with varying charts of accounts), and a Castaway excel budget which has an identical format for both stores.
In this case you would setup three sources for each unique chart, to look something like follows: