When viewing the Gantt chart you can change both how it looks and functions. To view settings, click on the 'settings' button to the top of the page to view the various options in the pop out window:
Auto Save - If enabled, the application saves any local changes every 5 seconds. If disabled, you have to save the changes explicitly. The option you choose only applies to yourself but will be the same across all projects you can access. Each user sets their own preference.
Skip Weekends - If you choose to enable this weekends will be hidden within the Gantt chart. Once you enable skip weekends you will also see a warning that you have tasks or milestones landing on weekends.
More information can be found here: Skipping weekends within the Gantt chart.
Show item name - Shows or hides the task, task list and milestone names on the chart. This will only apply to your own view.
Show assigned people - Shows or hides the people assigned to a task or a milestone on the chart. This will only apply to your own view.
Show task duration - Shows or hides the task duration's on the chart. This will only apply to your own view.
You can select how the tasks behave when dragged and determine how other tasks are adjusted, when one task is moved or resized. Tasks that are related via dependencies will be grouped together when moving.
Push all - All visible tasks related by a dependency move together by the same amount. Modifier key: Alt. (Ctrl+Alt on some systems such as Ubuntu).
Push some - The visible tasks related by a dependency are updated, if it’s necessary to avoid date conflicts with the other tasks. This was the default behavior up to now. Modifier key: Ctrl.
Push none - No other tasks are affected when one is moved or resized. Modifier key: Shift.
For more information see: Gantt chart