ltft stft fuel lean p0171 p0174

so i have stft that hover around .9 and then my ltft is at 1.20 which if im not mistaken means 20% correction to add fuel. how does ltft work on my sct x4. i want to understand what 1.20 means for ltft as i understand the stft of 1.00 is perfect and mine hovers around .9 but the ltft will...