You create email signatures for all users by inserting fields, which will pull information found in Employees menu.
You only need to insert the dynamic fields in your signature where employees will got their own data inserted:
((DisplayName)), ((JobTitle)), ((Mobile)), ((Email)) etc.
How to insert fields
Watch how to use preview to see how employee data is merged
If you have different company names and locations, then the information is effectively maintained for each employee in Employees menu:
If all employees are working in the same company and location, then you can remove the fields and just update directly in the template: