SSRS File share subscription, default credentials

Question

I'm using 2016 SSRS and have created a windows file share subscription. For some reason, any time I go in to modify the subscription, the default Windows user credentials changes from what I inputted (see image). I have to continuously keep changing the user name and reenter the password. Why is the subscription not holding on to the user name I specify? Is there some default setting I need to change?

windows credentials screenshot