XnView Software

When opening and editing pictures from Folders tab within XnView...I make changes and click the save button.

First, why doesn't it just save it? Why does it default to a Save As?

Second, why doesn't it default to the folder that I JUST opened the picture from? I only noticed because it didn't ask me if I wanted to replace the file, as it should during a save as. Not noticing this, it just saved the picture to a completely random folder. Makes me wonder how many times this has happened and where my pictures are. Very frustrating.

looks like you messed up the settings

default settings:
- Save - CTRL+S
- Save As - CTRL+SHIFT+S
- file's folder - the default path for Save As

ps. the default format for Save As is JPG for some reason, but thats another issue

How could I mess up the settings when I didn't change any default settings?

no idea
delete everything and reinstall app

if you used Catalog functionality - backup it:
- XnView.db - contains tags, rating&labels, categories and other file info
- (optional) Thumb.db - contains cached thumbnails

location depends on your settings:
- app folder OR
- C:\Users\<USER>\AppData\Roaming\XnViewMP