You can not edit or create categories in your Self Employed Quickbooks. They are based on the self assessment form for HMRC.
Resolution for 'category names issue: 'Can I change category names' available: Yes.
The category names 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 category names issue yourself by looking for a resolution described in the article. If it is a complex category names issue or you are unable to solve the issue, you may contact us by clicking here or by using other category names support options.
For more information about resolving issues related to category names in Quickbooks/QBO or to get support for the issue 'Can I change category names', click the link below: