Switching credentials during run-time

I have a report that I would like to switch between vendor's Production and DEV environments). I know how to make it dynamic for the datasources. I would use something similar to this:
="Data Source=" & Parameters!ServerName.Value & ";Initial Catalog=DBabc"

Is it possible to change credentials? The production and DEV environments have user id and password that are different from each other. How would I do this and still secure the password (credentials)? Also, I cannot prompt the users to enter password because we have to keep this secure.

what do you use to develop your SSRS reports?

SSDT Yosiasz. No Report Builder or .Net

you want to change this dynamically for deployment purposes? I think you could use expressions? Please check the following out. I never use SSDT

Unfortunately Yosiasz, that link pretty much covers what I had in my original post. The part that could be useful is at the bottom article: To pass credentials with the data source please read this.

But the link is no longer working. It is the credentials part that I need.