How to set dark or light mode for the stock chart page in the App:
On the [Market] page, tap any stock to enter the stock chart page. Then, click the [Settings] button at the bottom left of the chart, and select the [Theme Mode] option. You can then set the stock chart page to dark or light mode according to your personal preference.

How to set dark or light mode for the stock chart page on the Web:
Open the official website, click [Trade] - [US Stocks] at the top left, select any stock, then click the moon or sun icon at the top right of the trading page to set the stock chart page to dark or light mode.
