Pages will not speak text as specified

Running 10.15.07 Catalina. Recent convert to Pages from AppleWorks (which was a much easier and more efficient suite to use. Change - why?).

Imported and set up several Speech voices in System Preferences. Specified Siri voice. Tested it; it works fine in OS/Sys Pref screen.

Created document in Pages. Specified Siri voice (same one). Have used this with this exact machine within 2-3 weeks. BUT, now - system plays a different voice. Cannot change it back.

Deselected unwanted voice (did not delete) but Pages still speaks in that voice and in no other.

Followed Apple manual guidelines. There is NO panel in the Pages word-processing screen that permits any changes to voice. Question: how did I already, on this machine, specify a different voice for Pages than the one it stubbornly refuses to let go of?

FYI there have been system upgrades to OS. Is this related to a so-called 'improvement' upgrade?

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