Hey all, so i had two hands that i keep thinking about and where i am very uncomfortable as i dont know whats the aright play.

First hand:
PokerStars - $0.25 NL FAST (6 max) - Holdem - 6 players
Hand converted by PokerTracker 4

BTN: 100 BB (VPIP: 46.67, PFR: 40.00, 3Bet Preflop: 0.00, Hands: 16)
SB: 38.32 BB
BB: 112.48 BB (VPIP: 50.00, PFR: 50.00, 3Bet Preflop: 50.00, Hands: 4)
UTG: 113.08 BB (VPIP: 15.38, PFR: 15.38, 3Bet Preflop: 0.00, Hands: 14)
MP: 142.64 BB (VPIP: 21.05, PFR: 21.05, 3Bet Preflop: 11.11, Hands: 19)
Hero (CO): 116.28 BB

SB posts SB 0.4 BB, BB posts BB 1 BB

Pre Flop: (pot: 1.4 BB) Hero has K K

fold, fold, Hero raises to 2 BB, BTN raises to 7.52 BB, fold, fold, Hero raises to 19 BB, BTN calls 11.48 BB

Flop: (39.4 BB, 2 players) 2 A 9
Hero checks, BTN bets 12.44 BB, Hero calls 12.44 BB

Turn: (64.28 BB, 2 players) 5
Hero checks, BTN bets 30.68 BB, fold

BTN wins 61.4 BB

Am i overfolding here? I cant get away from a feeling that he has to have and Ace or its probably possible to have set of 9.
But i may miss played my hand from the beginning here.

---------------------------

Second hand:
PokerStars - $0.10 NL FAST (6 max) - Holdem - 6 players
Hand converted by PokerTracker 4

BTN: 93 BB (VPIP: 24.49, PFR: 20.41, 3Bet Preflop: 11.76, Hands: 51)
SB: 100 BB (VPIP: 12.50, PFR: 12.50, 3Bet Preflop: 33.33, Hands: 8)
Hero (BB): 208.7 BB
UTG: 105.7 BB (VPIP: 25.00, PFR: 0.00, 3Bet Preflop: 0.00, Hands: 17)
MP: 67.8 BB (VPIP: 12.50, PFR: 12.50, 3Bet Preflop: 25.00, Hands: 9)
CO: 107.7 BB (VPIP: 23.26, PFR: 19.77, 3Bet Preflop: 6.06, Hands: 87)

SB posts SB 0.5 BB, Hero posts BB 1 BB

Pre Flop: (pot: 1.5 BB) Hero has A A

fold, fold, fold, BTN raises to 2.3 BB, fold, Hero raises to 5 BB, BTN calls 2.7 BB

Flop: (10.5 BB, 2 players) 3 6 K
Hero bets 5 BB, BTN calls 5 BB

Turn: (20.5 BB, 2 players) A
Hero bets 5.9 BB, BTN calls 5.9 BB

River: (32.3 BB, 2 players) 8
Hero bets 9.2 BB, BTN raises to 77.1 BB and is all-in, fold

BTN wins 48.4 BB

Here im sure that opponent could have two pairs or just A with strong kicker, but i also couldnt get away from a feeling that he had stronger hand there with shove on the river just after that flush completed.

Hand 1 seems fine to me. Villain's range landing on the flop should be middling pockets, strong Ax and suited broadways. Presumably, middling pockets are not playing this board aggressively, unless it's specifically 99 ; and your hand blocks suited broadways. Which leaves strong Ax...

I don't know why you 3-bet 2X on the second hand.

Thanks for the feedback, yea for the 2nd hand I made an obvious mistake there, i have no idea what are correct bet sizings and need to work on that.

First hand you should do yourself a favour and range bet that board. Second hand yeah preflop sizing should be much bigger. Why do you 3b to 5bb and then yeah, maybe study a bit what postflop sizing should look like