Do you mean you want the calculations to only update manually?
If this is what you mean then you can go into the Formulas tab and click the Calculation Options button. Choose Manual. Alternatively you can also do this through File > Options and select the Formulas categories. At the top there is a section for "Workbook Calculations". Change this setting to Manual and you can select or unselect to Recalculate workbook before saving. Click OK and you will now need to press the Calculate Now button in the Formulas tab to have your calculations update.