Is it permissible to use the mouseover text display feature to write "Transferred Image" on images placed on a website, and is it sufficient to write "All these images are transferred" at the bottom of the page instead of writing it under each image?

There is no harm in taking pictures from the internet, provided they are attributed to their owners, regardless of the method of attribution. The important thing is that the effort is attributed to its rightful owner. It is obligatory not to publish pictures that contain or promote evil.