You can access the setting by taping Menu on the main command interface and More > Settings after that.

The settings menu allows you to manage sounds, game language and features such as:
Starting a new game: Note that this will reset all your current progress!
Linking in-game progress with a gaming service account.

If you wish to reduce the notification you can select any of the option to turn on or off. We are constantly trying to improve this section so the information will be valuable and informative for you, Commander

Warfare - when your city, resource tile or reinforced ally is attacked, scouted or combat has begun and when enemies retreat

Alliance - when alliance buildings are attacked or scouted; when new commands are issued and when technology contributions are available

Development - when construction, recruitment, recovery, crafting, part production or improvements are completed; whenever science points and general energy are fully recovered as well as as add-on ability cool-downs expire

Event - when events are about to start (Kill, Gather or Power events, Updates etc.)

Messages - when receiving a new message from alliance members or non-allied commanders

Benefit Passes - when Benefit Pass rewards are ready for collection

Protection - when protection boosters such as Peace Shield or Anti Scout are about to expire

Battery-saving Mode - Turning Battery-saving Mode "On" will allow your device to preserve more energy, so that you can concentrate on the development of your base and combat strategy. You will need to restart Instant War after switching the option on or off in order to apply the Battery-saving effect.

Back Button Position - The Back Button is used to navigate out of menus and its position can be set to two different positions based on your personal preference. The toggle in the Settings menu will allow you to choose between the Top Left Corner or the Bottom Left Corner.

Note: The Warfare and Alliance Spam Protection features allow to turn off notifications from attacks with less force than a value of your choice (up to 50K). Additionally attacks with lower force than the specified Spam Protection value will not trigger the in-game Alert Overlay.