How is pronunciation decided?

[iv2985]

Homographs like "wind" have different meaning and pronunciation depending on the context, but same spelling. For example "wind power" vs "wind a clock". How is this pronunciation decided in such cases?

It is pronouncing the "wind" in "wind power" the wrong way - the way it would be pronounced in "wind a clock". Strangely, it gets it right for the default voices, but wrong when I trained a new English voice.