How to open it a XnView?

[TurkishUser]

When using XnView, files with image extension are opened with Windows' default program, how can I prevent this?

[cday]

When using XnView, files with image extension are opened with Windows' default program, how can I prevent this?

Windows 10?

It may depend on the Windows 10 version, and is possibly becoming more difficult!

In general, an online search is a good first approach to Windows questions, here is one result from a quick search:

Change default programs in Windows 10

Whether that will work for you I don't know, if not a search including the version of Windows you currently have installed might produce a useful result.

[XnTriq]

Tools → Options… → Keyboard/Mouse → Open action (Browser) → Images:

• Open in associated program
• Open in XnView
• No action