Google Sheets – Changing Input Format for Dates in Google Docs Spreadsheet

Whether or not this is practical may depend on the formulae you are using (which you don’t show) but for something very simple like =Sum(A1:B2) you might switch to View, All formulae and replace ( with ($ and : with :$. Then transpose, repeat the process and transpose back. Otherwise “Search using regular expressions” may help.

I believe that the only way to achieve this is to set a locale in which this date format is a default one. For example I have it as default because I have Polish locale.

Link to settings: https://drive.google.com/settings