If you set up a delegate wallet then all of your presale access will be transferred to your delegate wallet when your primary wallet address is added to an allowlist.
The delegate wallet address does NOT change the primary wallet address associated with your account.
Users set up a delegate wallet address when they don't want to mint drops via their primary wallet address.
To set up a delegate wallet address click My Profile in the navigation bar on the left and select Edit Profile. Then scroll down until you see "Delegate Address".
Once you have pasted in the desired delegate address, hit save changes and you are good to go!