LHR/MEL/Europe FF's answer is as usual spot on. to add: there are two transit securities (where you move from arrival into departure area): East at conjunction of D/C/B/A concourses and West at conjunction of D/E/F/G concourses; so at both ends of the D concourse, which is around 800 meters long
EVA arrives/departs usually at E, F or G close to ist lounge, which is in F concourse; TG can depart from anywhere
So after Arrival, you should look out for your departure gate and head to the Closer transit security (on arrival level, there are travellators all along)