1.Go to company form view --> add a customized field  using studio(x_studio_im)

2.Go to general settings under "document layout"-->choose your layout(external_layout_standard)

3.open it(Edit layout), and add this code as shown in the pic below:

             <div class="row">
          <div class="col-12 text-right" style="margin-top:20px;">
           <img t-if="company.x_studio_im" t-att-src="image_data_uri(company.x_studio_im)" style="max-height: 45px;" alt="Logo"/>
          </div>
            </div>

4. save changes --> save settings

5. after refresh this page go check your new layout
from settings-->general settings--> under document layout-->"preview document"

6.finally you can check every report(invoice,sale order, purchase order)

Hope it will help you :)