why Apple's Common stock issued while Common stock outstanding decrease

The key is "and additional paid-in capital". When shares are issued, any amount the company receives above the par amount is "paid-in capital" and depends on the price at which the shares were initially sold (it is not adjusted based on secondary market price).

So the "common stock" balance is not just # of shares par but indicates how much cash was actually received in total - essentially it's # of shares avg price received per share.

The share repurchase is accounted for under "Retained Earnings" in the second group of items (which you do not show) on the Equity Statement.