iOS: How do I edit widgets?

You can change your widget data in settings.
For Watchlist widgets, you can choose any widget from your profile, change price change type (percent or price) and hide or show logos.,
For Symbol and News widgets, you can choose any symbol to be shown and also set the price change type.

To edit the homescreen widget, you need:,

Long tap on the widget, choose Edit widget

Edit the needed item, after closing, the setting will be saved automatically.

You can also change the settings of your lockscreen widgets through Customise mode.