Once you have multiple frames, you can move between them in various ways:
fnext
(C-t o or C-t TAB) jumps to the next frame in
the current group’s frame list.
fother
(C-t M-TAB) jumps to the last frame that had
focus.
fselect
(C-t f) displays numbers on each visible frame: hit a
number key or click it to move to that frame.
move-focus
(C-t <arrow key>) focus the frame in the direction of
the arrow key pressed.
sibling
(unbound by default) focus the frame from which the
current frame was split.