You need to use styles.
Press F11 and the Styles and Formatting windows pops-up. Select cells styles on the leftmost button. Select “Default” and right-button click on “Default”, then Modify.
The dialog that shows-up will allow you to set the attributes needed for all cells.
If you need this setup for specific new spreadsheet, then you need to save the above settings as a template, and open that template instead of opening a New spreadsheet.
If that template is to be the default template for every new spreadsheet, then go to Templates – Organize, select your desired template, open Commands and Set as Default