it's full banner i can't see any text banner
Why not it is possible, During the process of uploading your banner, check the below space you will see the desktop size and mobile size, you can easily input the range of the size you want the banner to be.
I think this should also help you to gain what you need to be done, if you did not get it, kindly message me with your store link to do that for you.
I have the banner H1 title hidden from everything using custom CSS
I wish to have the banner H1 title shown in mobile only?
I just login into your store now and I understand what you are saying but it is not about coding, it is something that you can easily fix by mere design, You need to study the type of theme used for Shopify and go to the admin, check slides area and collect what you need to fix out.
I think this should make sense to you now.