Every time I upgrade mIRC, it wipes out my settings
The mIRC installer preverves settings by default when upgrading. If mIRC was saving your settings correctly before upgrading, the most common reason for losing your settings during an upgrade is anti-virus software not recognizing the new version of mIRC and incorrectly deleting your settings because it thinks it might be a trojan/virus. This is called a false positive. Anti-virus companies normally update their databases shortly after new releases of software to prevent their software from doing this.
Unfortunately, if the anti-virus sofware has deleted your settings, it is unlikely that you will be able to get them back.
I go to Edit Server, enter everything correctly. I don't know what Login Method means, and the help box doesn't help.
Why can't it save my settings?
Do you mean that mIRC is not saving any new settings you enter into it now? Or just that you lost your settings on upgrade?