When performing an import into Salesforce, it is common to wish to import the created and modified dates, and the created and modified by users data. These are called audit fields, and they are not enabled by default in Salesforce. In order to import them, you'll need to follow the specific steps prior to starting your first import.
1. Login to your Salesforce account and go to Setup
2. Head to User Interface setup and check the box to enable audit fields
3. Under User permissions, create a new permission set
4. In the new permission set, edit the System settings to check the box to set audit fields
5. Manage assignments for your new permission set to add the user performing the import(s)