There is no definition on this subject in the IATF 16949: 2016 standard or the ISO 9001: 2015 standard. This issue may vary from company to company.
In some organizations, all training documents are stored by the HR department. In some companies, HR department stores only for office staff, and for workers who are production employees, the relevant department stores. In short, this subject varies according to the size and structure of the companies.