I am operating a Ghost blog using the AWS Lightsail app, which is convenient and great. However, I am having trouble uploading images when attaching them. Where can I change the localhost link to my real domain? (especially in case uploading images…) Please help me
Use ghost-CLI to change the domain:
ghost config url https://myrealdomain.com
It will rule all image upload have the URL https://myrealdomain.com/assets/images/image.png
Refer: Ghost-CLI - A fully loaded tool for installation and configuration
Thank you @cuongtran. I’ve restarted the ghost in terminal (AWS lightsail SSH) and finally the image is shown. I haven’t changed the any link. However, it is visible on the iPhone but not on the laptop. I am making efforts to resolve this issue. 
I wrote these in AWS lightsail terminal.
sudo /opt/bitnami/ctlscript.sh restart ghost
sudo /opt/bitnami/ctlscript.sh restart apache
sounds like a caching issue. Still seeing the problem?