Lynx invokes a built-in Line Editor for entering strings in response to prompts, in forms, and for email messages if an external editor has not been defined. Alternative key bindings can be offered by configuring with --enable-alt-bindings or by adding them in LYEditmap.c before compiling Lynx. If available, they may be selected via the 'o'ptions menu, or by editing lineedit_mode in the '.lynxrc' file.
Two such alternative key bindings, which may be available on your system, are the Alternative Binding keymap and the Bash-like Binding keymap.
Note: setting emacs/vi keys ON has no effect on line-editor bindings.
This is the Default Binding keymap:
ENTER Input complete - RETURN TAB Input complete - TAB, Do ABORT Input cancelled - Ctrl-G, Ctrl-O, (Ctrl-C on some systems) ERASE Erase the line - Ctrl-U BACK Cursor back char - Left-Arrow FORW Cursor forward char - Right-Arrow BACKW Cursor back word - Ctrl-P FORWW Cursor forward word - Ctrl-N BOL Go to begin of line - Ctrl-A, Home, Find EOL Go to end of line - Ctrl-E, End, Select DELP Delete prev char - Ctrl-H, DELETE, Remove DELN Delete next  char - Ctrl-D, Ctrl-R DELPW Delete prev word - Ctrl-B DELNW Delete next word - Ctrl-F DELEL Delete to end of line - Ctrl-_ UPPER Upper case the line - Ctrl-T LOWER Lower case the line - Ctrl-K LKCMD Invoke cmd prompt - Ctrl-V (in form text fields, only)  SWMAP Switch input keymap - Ctrl-^ (if compiled in) Special commands for use only in textarea fields: Textarea external edit - Ctrl-X e Insert file in textarea - Ctrl-X i Grow textarea - Ctrl-X g  "next" means the character "under" a box or underline style cursor; it means "to the immediate right of" an I-beam (between characters) type cursor.  Follow Ctrl-V with any recognised key command, to "escape" from a text input field.  For other key combinations using Ctrl-X as a prefix key, see the Help page for the Bash-Like Binding.