There is many different types of attributions (and attribution settings) in Adobe.
First, let's start off with Marketing Channel attribution...
This is similar to Google Analytics Source/Medium Attribute, the settings for this can all be found in Admin > Report Suites > (Select Suite) > Edit Settings > Marketing Channel > (multiple menu items here)
Most Important Items:
- Marketing Channel Manager - Allows you to define your channels and channel specific overrides
- Marketing Channel Processing Rules - Allows you to create the funnel down rules for your channels
- Marketing Channel Expiration - Allows you to set the expiry
OR, you might be talking about the Attribution on your Specific eVars... in which case you need to go to Admin > Report Suites > (Select Suite) > Edit Settings > Conversion > Conversion Variables
Each variable has its own expiry and allocation...
But don't forget, with the ability to do custom attribution in Workspace, it's recommended to try and keep your expiry more limited... it apparently works better if you use a shorter custom attribution...