There's nothing to modify, that returns data for one day.
Generally I eitehr use parameters or I derive dates, whereas your exampel is hard coding dates, which is not a good idea.
You can create a parameter of type range and then use soem thing like the following in the Report->Edit Selection Formula->Record
{table.date} = {?MyDateRange Parameter}
Then they can enter one day or many.
To derive a date, say for yesterday, use:
{table.date} = currentdate-1
Hope this helps, if not, try posting envirnmental and technical information:
Crystal version
Database/connectivity used
Example data
Expected output
-k