To change the Probability % Values to change when you select a Sales Stage you need to follow these steps;

1. Go to SETTINGS (Top Right, just hover over your name)
2. Select to expand the PICKLIST SETTINGS option (located in the STUDIO block)
3. Select the EDIT OPPORTUNITY PICKLIST option
4. Select the EDIT link next to the SALES STAGE field

This will display the Field options for the SALES STAGE field, which shows two columns.

The left column is the Sales Stage that has been set, and the right column displays the % probability that will be set when you select the corresponding Sales Stage.

Note : Remember to line the values up correctly.

SAVE and then test by changing an Opportunity Sales Stage and see the Probability Value change also.