Choose between Traditional, Taiwan and Hong Kong presets

The four presets

Column headings are the source text; dots mark the characters each preset changes. The Simplified Chinese row converts the Taiwan result back: the characters change, the Taiwan terms stay. All examples are actual OpenCC 1.4.2 output.
Preset	他们一起吃面	床上的温度计	What it does
Simplified Chinese	用滑鼠開啟軟體裡的影片用滑鼠开启软体里的影片		Produces Simplified characters. It is not a complete reverse conversion of Taiwan-specific words or phrases.
Traditional · OpenCC	他們一起喫麪	牀上的溫度計	Uses OpenCC's standard Traditional form. This is an internal conversion standard, not a promise to match every Taiwan or Hong Kong usage.
Taiwan · Standard + Idioms	他們一起吃麵	床上的溫度計	Applies Taiwan character variants and Taiwan phrase conversion as well as Simplified-to-Traditional conversion. Choose it when the intended readers use Taiwan writing conventions.
Hong Kong · Traditional	他們一起吃麪	牀上的温度計	Applies Hong Kong character variants. The preset does not add a separate Hong Kong idiom option in OpenCCman.

Know your audience. For Taiwan-facing copy start with Taiwan Standard with idioms; for Hong Kong-facing copy start with Hong Kong Traditional.
Keep an original. Compare the source and result, especially for names, brands, quotations and technical terms.
Use advanced controls only when needed. Other combinations appear as Custom. Change one setting at a time and reconvert so you can see its effect.