Saved only in this browser. They apply to the page audit, the website scan and the site analysis.
Limits protect the website you scan: at most 4 parallel requests and 500 pages, with a pause between requests. If a server answers "429 Too Many Requests" or 503, the crawler slows down automatically.
Lengths are display guidelines, not ranking rules.
Disabled checks are removed from audits, scores and exports (the report lists which ones were disabled). A severity change only changes how much a check weighs in the score.