Inside WPS (Kingsoft’s documented path)
- Open WPS Office.
- Settings (upper-right on the home page).
- Component Management → File Format connection.
- Clear Compatible with third-party software if you do not want WPS as default.
- Restart the PC if associations do not refresh.
To go the other way, tick that same box. Source: WPS Help: enable/cancel opening files by default.
Inside Windows 10/11
- Settings → Apps → Default apps.
- Search for .pdf, .docx, .xlsx, .pptx one by one.
- Pick Edge, Acrobat, Word, Excel, PowerPoint, or another app.
- Or: right-click a file → Open with → Choose another app → Always.
Linux hint
Community configs use a flag in Office.conf along the lines of not detecting file associations at startup. After that, set mime types in your desktop (GNOME Settings, KDE File Associations, xdg-mime).
macOS
Get Info on a PDF → Open with → Change All. Repeat for DOCX if needed.
Why installers do this
Owning .pdf and .docx is distribution. Every double-click is a chance to show the suite — and the upgrade. That is rational for Kingsoft and annoying for you if you paid for Acrobat or Word. You are allowed to refuse. You must refuse in two places because Windows and WPS both store a vote.
How to verify you won
Create a tiny test.pdf and test.docx on the Desktop. Double-click. Note which icon lights up. After a WPS update, do it again. Updates are when associations come back from the dead.
If you do not have admin rights
You can still Open with → this time only. You may not be able to Change All. Ask IT for a default-apps policy. Do not install a second “PDF fixer” utility from an ad; it will also want to be default.
Browsers also steal PDFs
Chrome and Edge want to preview PDFs. That is a separate default from WPS. If you “fixed WPS” and PDFs still do not open in Acrobat, check the browser too. Three voters: WPS, Windows, browser.