Clicking on Products -> All Products menu at the left menu bar or All Products in the middle of dashboard page take you to the manage products page.
Choose all the products by selecting check-boxes and click on menu Actions -> Bulk Edit
The selected products will be shown with editable fields like below. You can do the required modifications and click on Save button to complete the modification process.
Please note that you can adjust the fields type for modification like shown in the below screenshot.
