Thanks Joe. Yes it could be a solution but I would like to keep the same format for each value.
You can format the text box however you want it to display.
But you're not going to get it to happen in you sheet itself. If there is nothing to display, Tableau isn't going to display anything.
Keep in mind that a sheet in Tableau isn't like a sheet in excel. In excel a cell exists because you say it is there. In tableau a cell exists only when data exists in the defined row on the sheet.