Powering Servos (help)

So I know this question has been asked quite a lot but I'm really conflicted with everything that I've read. As far as I know, servos require a surprisingly large amount of current, I am using a single 9V battery right now and I've read so far that it isn't powerful enough (I've tried using the 9V battery to power 2 servos, one of them works fine but the other usually lags or jitters). However, a single 9V battery is what the tutorial I followed used (unless I misunderstood something I'm quite new to all this). So now I'm thinking of getting a 4 AA battery holder to power the servos but I'm trying to make sure that I don't make the same mistake again. Anyone can help?

My project is a robotic arm that uses 4 SG90 servos in total.

Servos can draw about an amp or so Each.
9V battery has about 300-400mAH capacity. Barely enough to run one servo.
Use a 4x AA battery pack, or 4x C battery, or 4x D battery, that will provide enough current for more than just a brief amount of time.

This took some searching to find, but it shows the servo current under a couple of conditions;

Running current 220 ± 50 mA
Stall current 650 ± 80 mA

So, moving with a heavy load could ne 270mA, and attempting to move while jammed up could be 730mA.
Moving from a dead stop could also require currents near the Stall current.

You can see why a 9V battery intended for low current draw & longish life (like in a smoke detector) would not last very long with a servo, which is drawing high currents and for longer durations.

4 x AA NiMH rechargeable batteries (Eneloops or similar) are what you want. Rechargeable batteries have a greater ability to supply current than standard 1.5V alkaline batteries. And 4 x 1.2V batteries can run both the servos and the Arduino directly via the 5V pin if that is important to you.

You can use 4 x 1.5V standard batteries to power the servos but then you will need another way to power the Arduino. That 9V battery might do provided you ONLY want it to power the Arduino, not servos or too many other components.