Faulty Fonts

Anything in System Preferences > Keyboard > Text that is seeing 'as' and replacing it with 'z'? The designated Input Source in that Keyboard panel? Also, what is the Preferred Language in System Preferences > Language & Region?

Just a guess, as you've not provided the details that might point to the actual cause…

Check System Preferences > Keyboard > Text to see if this is the result of a text replacement setting:

With the two shown in the image, if I type c b x (without those spaces) the result is ▢ and two consecutive = signs are replaced with a dash − . The replacement occurs as soon as I add a space (or other 'word end' indicator after the trigger text.

Regards,

Barry

Graham Giles wrote:

Every time I type 'as' in emails, text edit, Pages etc. the computer gives 'z'.

Nothing to do with fonts, and first time I have ever seen it reported.

In TextEdit, go to Edit and make sure all spellcheck and substitutions is turned off. Does it still happen?

Graham Giles wrote:

Yes that's fixed it in Text Edit, emails, and Word - but not in Pages

Are you perhaps confusing Pages and Word? Pages has basically the same Edit menu items as Text Edit. Word doesn't use Apple stuff, and if you are having a problem in Word you have to look inside its own preferences.