Files typically open with unexpected applications when your operating system’s default file associations are changed. Each file type (identified by its extension like .jpg or .pdf) is linked to a specific program. This setting controls which app automatically launches when you double-click a file. If an app update, software installation, or manual setting change alters this link, your file may open incorrectly.

For example, installing a new photo manager could reset .png files to open with that app instead of your preferred editor. On Windows, iOS, Android, or macOS, a system-wide preference (like "Open with > Always") might override your typical settings. This also occurs when transferring files between devices with different default apps, such as opening a video file on a new computer where the default player differs.

The primary advantage is automated convenience, but limitations include user confusion when settings shift unexpectedly. Future developments aim for smarter detection (like content-based defaults) to reduce errors. While not an ethical concern, frequent mismatches highlight usability challenges, particularly for less technical users. Regularly reviewing settings post-installation helps maintain intended functionality.