How do I determine which Photo editing software I that I have on my Dell laptop
You might try right clicking any image file (.jpg, .png, etc.,) and checking the context menu when you select "Open with" most of your image programs should be listed there.
I don't know if it's exhaustive but it should give you some idea.
Someone I am sending photos to says she can not copy them in her software, but she can open them.
It may be more an issue with her software rather than yours.
Assuming you are sending them in their traditional format / file extension.
IF she can open them then perhaps she could save a local copy on her device rather than "copying" them.
Not sure why she is copying them