Editors treat synonyms like spices — the wrong one can change the whole dish. I often approach picking a synonym for 'credibility' by imagining who will read the piece and what kind of trust the text needs to build. Is this for a peer-reviewed paper where 'validity' or 'reliability' will sit comfortably? Is it for a personal profile where 'trustworthiness' rings truer? Thinking in those terms helps me narrow candidates from a long thesaurus list down to the few that actually fit the tone.
I also run practical checks: I substitute the word into several real sentences to hear it aloud, scan corpora or quick Google examples to see natural collocations, and weigh connotations. 'Authority' carries institutional weight and can imply power rather than honesty; 'plausibility' signals something epistemic and tentative; 'believability' is more colloquial and sometimes dismissive. Those shades matter—especially when the audience is sensitive to precision, like researchers, or when a marketing context needs more human warmth.
In my editing toolkit I keep a few go-to resources: a trusted dictionary for definitions, a usage guide for register, and a collocation tool or plain web search for real-world examples. I also check surrounding modifiers (you say 'high credibility' but rarely 'high plausibility' in the same contexts) and ensure grammatical fit. The moment a synonym reads awkwardly or skews the meaning, I scrap it. Choosing synonyms is partly craft, partly judgment; the right word makes the text feel honest and clear, and that’s always satisfying to me.