Change General preferences in Messages on Mac

Keep messages

Choose how long to keep message conversations in your account. For example, if you choose 30 Days, your conversations (and all attachments) are available in Messages for 30 days. After that, they are automatically removed.

See Save or delete text conversations.

Save history when conversations are closed

Select to save your conversations when you close them. If you don’t select this option, closing conversations deletes them. Quitting Messages or closing the Messages window doesn’t close individual conversations.

Notify me about messages from unknown contacts

Select to receive a notification whenever anyone contacts you. If you don’t select this option, you get a notification only if you’re contacted by someone who is listed in Contacts or is someone you previously received messages from.

Notify me when my name is mentioned

Select to receive a notification whenever your name is mentioned in a conversation.

Play sound effects

Play the default sound effect for when any event occurs. For more details, see Play sound effects.

Message received sound

Choose the sound that plays when a message is received.

Save received files to

Choose where you want to store files sent to you by friends in Messages.

Text size

Move the slider to adjust the size of text in Messages.