Places you can configure the sender's email:

Manual emails

Conversation tab

The From email will be the user logged in email by default:

Places you can configure the sender's email:

Automated email

Email template

Navigate to Marketing -> Emails, select (+ New), then Select the design editor and create a blank template, or edit an existing template by clicking on its pencil icon

Once you created the email template, click Settings from the 3 dots menut and configure the From name/address here

Bulk action - Send Email

Click Contacts ->Smart Lists -> Select Contacts -> Click Send Email

Add the From Name and From Email

Workflow settings

Click Automation -> Workflows -> Create Workflow or edit an existing flow

If creating a new flow, Select continue in the tile to Start from scratch

Click Settings and configure the sender details area and save the workflow

Workflow Send Email Action

Click on the + button > Select the "Send Email" option

Enter the From Name and From Email