I don't think you can change the default, but since excel likes to remember the
last thing you did, you can take advantage of it.
Start a new workbook and record a macro that does a Find the way you want.
Then name that macro: Auto_Open
and right near the last line, add this: thisworkbook.close savechanges:=false
Here's the format (but don't trust the settings--use your favorites!):
Option Explicit
Sub auto_open()
Worksheets("sheet1").Cells.Find What:="", After:=ActiveCell, _
LookIn:=xlValues, _
LookAt:=xlPart, SearchOrder:=xlByColumns, _
SearchDirection:=xlNext, MatchCase:=False
ThisWorkbook.Close savechanges:=False
End Sub
Save this workbook in your XLStart folder. Each time you open excel, it'll run
a "dummy" find. And excel will remember your settings--until you change them.
If you're new to macros, you may want to read David McRitchie's intro at:
http://www.mvps.org/dmcritchie/excel/getstarted.htm