I noticed others here have given some good suggestions, so I'll add a few as I know how frustrating a noisy bird can be. If you had a conure then you certainly know about noisy birds and also about manipulating the reward center of the brain to get desired behavior over time. With birds training is unquestionably more of a challenge - my uncle trained parrots for Busch Gardens in Tampa the 60s and I learned a lot from him.)

Typically pet parrots (as apposed to those in the wild) never "scream" excessively. Humans cohabiting with parrots is another story. There are many things that will make them get noisy. I go through a long mental list. Hunger ritual. Is she protesting over the food, a change in my routine or simply bored? Did I change the food mixture to something she doesn't like and so she's not eating? Did I forget the time and is she waiting on me to eat with her? (Yes, believe it or not some birds wait to eat with their human companion and I have an eating ritual with mine.) Birds are sensitive to our rituals like eating habits, play, and other predictable experiences that make up their daily routine. When these rituals are disrupted or changed, that's a possible source of the screaming. Security. Birds tend to be happier in rooms with stimuli like kitchen noises, radios and TVs - and where they can see you. So relocating the cage can obviously help. Also, I have developed a clicking call signal I trained her to use when I leave the room and she wants me to come. If she screams, she gets no direct attention or eye contact from me. I have a Jenday and she does still scream occasionally, but overall she's very good as long as I stick to our agreed upon eating rituals. As for your apartment situation I empathize - I've been there. It's definitely harder working with a bird in an apartment - there are fewer options and less to stimulate a bored parrot. I rotated her toys and treats a lot. (Actually, adjusting and changing a bird's cage really affect parrots, because they come to see the cage as sort of their "territory", and yet they see you take it all apart, clean it and fill it with food and toys. It triggers the nurturing instinct in seeing you as their "parent provider" and it calms them. (Have you ever noticed that a bird acts very different when returned to its cleaned cage? That's why - safety and security.)

Physical. Still, all that said, there are occasions when I have no idea what is triggering her noisiness and assume it's just her hormones (knowing I've cared for her other needs). If she gets too noisy I put her in my bed room where it's calm and quiet and I keep a small travel cage ready with water, food and a happy hut and I cover her there. After a few hours in a nice quiet place with no abrupt noises when she can give herself a rest, she feels better and is much quieter. I also use this technique when I know she's not feeling well to nurse her health. One last thing - you did mention she is 9 months which is about right for puberty being at its pinnacle and the sex hormones kicking in. Whenever playing and she shows signs of "flirting" then quickly return her to her cage and end play time. You don't want her to view you as a sex partner but more of a father figure and provider. This also suppresses the screaming behavior. If you use a happy hut (which imo they are fine) remove it during the day until she reaches full adulthood. I have lived around birds all my life and rest assured this screaming phase will pass - just requires time and nurturing.