90) The need
91) Your subtitles are simplified Chinese and have to reach viewers in Taiwan or Hong Kong. Fixing the characters one by one is not realistic — a single episode has hundreds of cues — and the two regions do not want the same traditional text: the vocabulary differs, and the wrong direction produces wording no local would use.
92) Where to do it
93) Open Simplified–traditional conversion, drag the subtitle in, and pick one of the simplified → traditional direction under "Convert to": generic traditional, Taiwanese (change wording), Taiwanese (glyphs only) or Hong Kong. Conversion happens instantly and the result area shows the finished subtitle, ready to download.
94) For a Taiwanese audience: choose "Taiwanese (change wording)" if regional vocabulary should change too — "software" and "information" become their Taiwanese equivalents — or "Taiwanese (glyphs only)" if you want the character shapes changed while keeping your original wording. For a Hong Kong audience: choose "Hong Kong", where "software" is written with yet another form.
97) Common pitfalls
98) Do not fear one-to-many mappings: the same simplified character in the words for "clean", "dry" and "tree trunk" maps to different traditional characters. The tables resolve this by phrase, so everything is not flattened into one character.
99) Only dialogue is converted: timings, index numbers and ASS style lines are untouched, so the result is ready to use.
100) Nothing changed? Check before you panic: if the stat bar reports 0 changed lines, either the file has no Chinese characters or the format was mis-detected — check that "Detected format" matches what you uploaded.
101) Related
102) The full explanation of all nine directions — How to convert simplified and traditional subtitles; why it is more than swapping characters — Simplified vs traditional is not a character swap; traditional back to simplified also lives in Simplified–traditional conversion.