The default sender address of your PayPal account is taken from the your PayPal account registration address.
PayPal account and PayPal shipping account
Your PayPal account and the PayPal Shipping account are two different platforms connected to each other for shipping purposes. This allows effortless importing of your items sold on PayPal into PayPal Shipping. However, they still remain two different platforms.
PayPal Shipping takes the registration address from your PayPal account.
Default shipping address on PayPal Shipping
In case you want to change the sender address to PayPal bulk shipping > settings > warehouses. This will allow you do set a different sender address for your shipping needs.