-e xy
specifies the command character to be x and the character generating a literal command character to y (when typed after the command
character). The default is “C-a” and `a’,which can be specified
as “-e^Aa”. When creating a screen session,this option sets the
default command character. In a multiuser session all users added
will start off with this command character. But when attaching to
an already running session,this option changes only the command
character of the attaching user. This option is equivalent to
either the commands “defescape” or “escape” respectively.

defescape xy
Set the default command characters. This is equivalent to the “escape”
except that it is useful multiuser sessions only. In a multiuser session “escape” changes the command character of the calling user,where
“defescape” changes the default command characters for users that will
be added later.

escape xy Set the command character to x and the character generating a literal command character (by triggering the “Meta” command) to y (similar to the -e option). Each argument is either a single character,a two-character sequence of the form “^x” (meaning “C-x”),a backslash followed by an octal number (specifying the ASCII code of the character),or a backslash followed by a second character,such as “\^” or “\”. The default is “^Aa”.