Gmail account settings
From the Home screen, Google folder
> Gmail 
> the Accounts
and labels icon 
(at the upper-left corner of the screen).Tap Settings.
Tap General settings to change the following settings for all accounts.
Gmail default actions: Sets if you want to display only the archive option, only the delete option, or both options.
Conversation view: Groups emails in the same conversation together when using IMAP and POP3 accounts.
Swipe actions: Checkmark to archive a conversation when you swipe it.
Sender image: Checkmark to display the sender’s image to beside the name in the conversation list.
Reply all: Checkmark to make Reply all the default message action.
Auto-fit messages: Checkmark to shrink the messages to fit the screen and allow zooming.
Auto-advance: Sets which conversation list is viewed after archive or deletion. Choose from Newer, Older and Conversation list.
Confirm before deleting: Checkmark to ask to confirm before deleting a message.
Confirm before archiving: Checkmark to ask to confirm before archiving a message.
Confirm before sending: Checkmark to ask to confirm before sending a message.
Changing specific Gmail account settings
From the Home screen, tap Google folder
> Gmail > the Accounts
and labels icon (at the upper-left corner of the screen) > Settings.Tap a Gmail account to change the following settings for that specific account.
Inbox type: Sets your Inbox type. Choose Default Inbox or Priority Inbox.
Inbox categories: Sets where specific types of messages (e.g., messages from your social networks or promotional offers, etc.) are stored into Inbox categories.
Notifications: Checkmark to display notifications for new gmail messages.
Inbox sound & vibrate: Sets synchronization settings and notification settings.
Signature: Sets the signature you want to include with every outgoing email from this account.
Vacation responder: Sets up an automatic email to respond with when you are out of the office (or otherwise unavailable). Tap the switch to turn it on, enter the dates for the responder, and enter the subject/message.
Sync Gmail: Checkmark to automatically sync your account.
Days of mail to sync: Sets how many days of email you want to sync.
Manage labels: Sets the sync and notification settings for each of your labels.
Download attachments: Checkmark to automatically download attachments to recent messages via Wi-Fi.
Images: Sets when to show images included in your Gmail messages. Choose Always show or Ask before showing.