I had exactly this problem. So unquestionably Excel formulas are very vital in Microsoft Excel. If an Excel spreadsheet displays all its formulas within cells the Show Formulas option is probably enabled.
To check if Show Formulas is turned on visit the Formula tab in the ribbon and check the Show Formulas button.
The reason Show Formulas can be accidentally enabled is because it has the keyboard shortcut Control that a user might unknowingly type. Changing Calculation option to manual is. I had exactly this problem. Thank you youre great I lost one jour looking for a solution.