Default macro startup file

I created a macro for a read-only workbook that I stored into "Personalmacro.workbook" so that I could use the macro every time I got an updated version of the read-only workbook. Now, everytime I start Excel, instead of a generic "workbook1" file, "personal.xls" starts instead. How can I stop this from happening? I would just like the default reset to "workbook1". Thanks for any help.