We discuss the large extent to which ionic impuritics and previous states influence the switching of ferroelectric liquid crystal cells. In particular we see that the ionic field built up in response to the molecular dipoles causes switching to correlate with the previous state. This memory effect is not crasable even when the cell is fully reset into a uniform state. Also the strength of the reset pulse influences the ionic field and generally causes enhancement of partial switching in the opposite direction. There also exists an anomalous region where this enhancement doesn‘t occur. This is apparently due to variation in the elastic stability even when the cell appears to be in a uniform relaxed state.