You can add custom fields to companies this way :
- Go to the General --> Settings --> Company settings --> "Custom fields"
- Add the fields that you want (this works the same as other custom fields. You may also need to add a section if none exists.)
- Go to General --> "Companies" where the fields now should be available on the company card
To add the new fields to the table grid in Companies:
- On the table column header click on the down arrow icon (on the right of a column)
- Choose "columns" in the menu that open
- Select the new columns/fields that you want to show
- The new fields should now be shown.
Note: To use custom fields on company, you must use/purchase the CRM module. Check General - Settings - Additional features, to see if you have this module activated.