How to change the number of sheets for new workbooks
For example, if you prefer to start each new workbook with two worksheets. After all, it's easy enough to add new sheets if and when they are needed.
To change the default number of worksheets, do the following:
1. On the File tab, click the Options button:

2. On the General tab, in the When creating new workbooks group, change the value for the Include this many sheets field:

3. Click OK.
Note: Making this change will affect all new workbooks, but will not affect existing workbooks.
See also this tip in French: Comment modifier le nombre de feuilles pour les nouveaux classeurs.