I don't see a reply button for you Andreas, so I'm doing the "Answer". Thank you Andreas for your response. I'll try to address your questions. Because it's not a reply, hope you see it.
Yes, this is IDS on Windows. We are updating our platforms. But that is on an older machine. This is a newly configured 2019 server. Meant to install Informix and test on. This is not an upgrade. It didn't have Informix on it before. But, I have installed it and removed it several times to choose the right options to get what I wanted. AND capture the screens for documentation.
Before installing, I removed both the CSDK and IDS. And even though I requested a complete uninstall, it left behind directories, which I moved to a completely different directory (in case I needed something). Then I removed the informix and ifxjson users as well as the groups (Informix-Admin and Informix-JSON) it created.
I did choose Local users. AND, I clicked the DR box (even though we aren't doing replication) because apparently it doesn't create the informix user if I don't. Only the ifxjson user. I what I checked, because I have screen caps.
For normal use, this is using FourJs. Everything is running on this server. We don't need domain users. Local is fine. We have the SSH setting up temp users - also locally. And because we have other servers, I'd rather not have a password get changed and, as you described, have to go mess with all of the services. This machine is separate, so don't want it affected by domain changes.
Although I did check local users, how I find them is in the Active Directory Users and Computers program. Listed with the computer name\informix as if it's domain name.
Also I am doing this as administrator. I have not added either of the Informix groups it added to the administrator user. I thought administrator was allowed regardless.
I look now, I see that my old 11.70 instances have the _dat added to dbspaces as well. But like I said, that's not a big deal. When I install a regular instance (and clients will probably only have one) and tell it the data space is called user1, it doesn't add the _dat. But when I tell the instance installer that it's user1, it does.
Exploring the Informix Multiresidency documentation. Wondering if there's command line options to do all this and if it behaves differently from the GUI.
Wondering. Seems that I can run the installer with the -f <ini_file>. And that I can supply a few options, but not everything and it'll take defaults from the ini file. I'm not certain, but google AI generated a sample and from it I glean it could look like this:
[Installation]
INFORMIX_USER=<machine name>\informix
INFORMIX_PASSWORD=<my informix password>
So if just plain informix is the problem, I can use this to specify the machine name\informix as the user and specify the password. The -f option for instmgr.exe apparently tells it to get some things from the ini file, then prompts the user for the rest.