Click your profile photo in the bottom left.

Do you need to be notified about all new messages in all your channels? Probably not. Consider instead choosing "Direct messages, mentions, & keywords."

Choose a timeframe to receive notifications that fits your schedule.

For very high priority channels (maybe your team channel or the #reporting channel for engineers), you can override the above settings.
Click here

For very high priority channels (maybe your team channel or the #reporting channel for engineers), you can override the above settings.

To change the notification settings for a specific channel, right click on it.

Slack

By default, Slack can be very distracting. Your coworkers typically do not expect you to be instantly available across channels. Configure Slack notifications to make your life better and more productive.

How to Manage Your Slack Notifications