Computer

1. On your computer, sign in to Google My Business. 
2. In the menu on the left, click Photos.
3. Under the “Overview” tab, 
   • If no Cover has been added before, you will have the “Cover” card, click Choose photo.

• If you have a Cover already, press on the pencil icon next  to ”Cover”  to change it

4. The set cover pop-up box  appears:

5. You can either drag the cover or click on the blue button “Select a photo from your computer” to open the “file explorer”.  Tip: if you want to use a photo already uploaded, you can do it on GMB App.

6. After you selected the image file for your cover, the process is finished

GMB App

1. Open the Google My Business app 
2. In the bottom right, you tap Post 

3. Press on “Add photos/videos”

4. Tap on “Add photo or video”. 

5. Choose the type of photo or video you want to add: take a new photo or choose from a Gallery, as we are talking about the Cover the latter makes more sense.

6. Choose your Cover image

7. When you have chosen the image for your cover, you go into a very simple photo editor, press on the ”Next” button

8. You can add a caption to your Cover, just press “Add Caption” – You should add your business name Cover + main service/product + main city/town. When finished, Tap Upload 

9. Then go and press “Profile” » press “Photos and find the image you uploaded to set as a Cover.

10. In the top right corner of the photo, tap More (three vertical dots). To add or edit a Cover photo: Tap Set as Cover.

Uploading the image that you want as your cover photo doesn’t guarantee that image will be selected by Google as the “cover” photo,but it does tell Google you prefer to display this photo.

If after a couple of weeks the cover photo you uploaded is not showing as the “Cover”, you try the tips I have in my Google My Business training.