I apologize but i am not sure i fully understand the question. ┬áIf you want to add custom fields to a customer record, you would turn on the custom fields in the “My Field Labels” area of company preferences (requires the pro version or multi-store).

But since you also mention discounts, […]

Resolution for 'add fields issue: 'How do I add/edit custom fields? When I select a customer, apply a discount, how do I add fields for where to assign the discount to?' available: Yes.

The add fields issue or error code is a known issue in Quickbooks Online (QBO) and/or Quickbooks. Support for this issue is available either by self-service or paid support options. Experts are available to resolve your Quickbooks issue to ensure minimal downtime and continue running your business. First try to resolve the add fields issue yourself by looking for a resolution described in the article. If it is a complex add fields issue or you are unable to solve the issue, you may contact us by clicking here or by using other add fields support options.

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