Update Connections via Rest API using variables?

Summary:

I'm trying to set up a Rest API call to update connections in cloned environments and can't figure out how to get the call to work passing variables in the parameters.

Content (please ensure you mask any confidential information):

We clone 5 pods to QA pods every week and then have to update the connections manually in each of these pods. I'm trying to automate this using Rest API but don't want to have to input the password manually or in every call. We have a password file with the encrypted password for use in EPM Automate scripts and I can retrieve the encrypted password from that and assign that value to a variable, but when I try to pass the variable in the parameters of the Rest API call it tries to pass the variable name