"I saw the increase in quality straight away."
Translation:Я сразу увидела рост качества.
Я видела рост качества means that you saw it some time in the past and probably observed it for some period of time. If you saw it once and at some moment it is увидела. In this sentence 'straight away' indicates a single and a very short action, the increase in quality was noticed rather than observed, that's why увидела.