After installing Helvetica Neue font onto my PC (Win7) it now appears almost everywhere online in the interface of websites?

Unless a web page uses a “web font” that it supplies itself, web pages typically provide a list of fonts, in priority order, of fonts to be used to render text. Typically, this list of fonts represents “system fonts” of MacOS, Windows, iOS, and Android - fonts that can be counted on being installed. Helvetica Neue is a MacOS system font that is not typically found on Windows systems. And even if a user licenses recent versions of Helvetica Neue OpenType fonts and installs same on Windows systems, they are in the “Helvetica Neue Std” family which would not match “Helvetica Neue” which is native to MacOS. Thus, I suspect that the Helvetica Neue you have installed on Windows is an older font offering.

There are three issues here:

The first is that web pages provide a priority list for font usage. I suspect that the web pages you are seeing Helvetica Neue actually used on your system are requesting fonts in the order of Helvetica Neue and then Arial. The typical MacOS system would display the content with Helvetica Neue and the typical Windows system would display the content with Arial. Since you have Helvetica Neue on your system, you are getting rendering similar to what a MacOS system would have.

The second issue is that there is no way to force a web page to reverse the order of priority of the fonts it lists.

And finally, the third issue is that there is no way to hide a font selectively by application.

The only way you can avoid Helvetica Neue being used on web pages preferring Helvetica Neue to let's say Arial or any other font on its list for particular text rendering is to uninstall Helvetica Neue.

That having been said, other than perhaps personal type design preferences, are there any other issues with regards to use of Helvetica Neue for display of these web pages?

        - Dov