I typically use a formula to get a default value to appear in a cell, even if the cell also has a DV list to allow quick access to other options.
Just turn off the ERROR ALERTS in your DV settings long enough to enter a formula, something like this to watch for column A to start a row of data, so if A2 had a value, this formula in B2 or C2 or anywhere on the row:
=IF(A2="", "", "Apple")
Once you have the formula installed, you can turn back on the error alerts if you want.
Keep in mind the formula is there and working until someone uses the DV list to make a selection, after that the formula is gone for that row, which is probably fine.