Enable 'Supply Default Opportunity Line Item Values'

To enable the 'Supply Default Opportunity Line Item Values' feature for your organization:

1. From Setup, type "Opportunity Settings" into the Quick Find box
2. Select Opportunity Settings
3. Check the "When users add a product to an opportunity, insert a quantity of 1" box
4. Save.

Overview of 'Supply Default Opportunity Line Item Values' and post-activation use

Once the feature is activated for your organization, consider the following details:

• While this feature is enabled, we recommend not removing the 'Sales Price' field from Opportunity Product page layouts.
• The 'List Price' field value from the Price Book will be set as the default value for the 'Sales Price' field (which can be edited later).
• If the 'Quantity' field is removed from the Product page layout and Product multi-line edit layout, the field defaults to a value of '1.' Prior to activation of this feature, you have to manually enter values into this field.
• The 'Sales Price' or 'Quantity' fields can be removed from:

1. The Opportunity Product Page Layout
2. The Opportunity Product Multi-Line Layout (occurs automatically with (a))

Note: The  'Sales Price' or 'Quantity' fields, once removed, can be re-added to the Page Layouts individually (first to the Opportunity Product Page Layout, then to the Opportunity Product Multi-Line Layout).
When the Quantity field in the Opportunity Line Item object is updated, the Sales Price will need to be on the page layout to be evaluated in Lightning. When the Quantity field is updated without specifying the Sales Price on the page layout, the Sales Price will be adjusted to accommodate the new Quantity value, and the TotalPrice will be held. This is expected behavior. 
 If the 'Sales Price' or 'Quantity' field is present in the Opportunity Product Page Layout, it will always be present on the Multi-Line Layout. Review, Edit Multi-Line Layouts for Opportunity Products.

Cannot make the Sales Price or Quantity fields optional even though the 'Supply default opportunity line item values' feature is enabled

For organizations with the 'Quotes' functionality

If your organization is using the Quotes functionality, the 'Sales Price' and 'Quantity' fields are still required. Currently, there is no feature to make these fields optional for the 'Quotes' or 'Order' objects.

If you would like to vote for this functionality, please see the Sales Price field on Quote Line Item object not required posting on the IdeaExchange.