If a friend on Keep&Share has shared something with you and they want you to edit it, first that person must give you Edit Rights. “Edit Rights” are part of the Share Control for each of the applications in your account.
When you share anything that you have created in Keep&Share, there is a column in the Share Control labeled “Can Edit” with a checkbox next to each name in your Share Control. When you click on these checkboxes, you are giving people the ability to changes and make edits to items in your account. If you click on the "Can Edit" checkbox at the top of the column you can select all of your friends in your Share List at once to give them Edit Rights.
By default, the person that owns the content will be the only person who will have the ability to edit any of your content on Keep&Share. You will have to go into the Share Control to give anyone else Edit Rights.
Learn more about how you can access content in another person’s account.