Trados Studio - Project-level Verification settings do not override the settings changed at language pair level

You are customizing the settings from Project Settings > Verification which are propagated into the language pair level (Project Settings > Language Pairs > [your language pair] > Verification). Then you modify the settings at the language pair level and add new changes to the project-level Verification settings.

The latest changes done under Project Settings > Verification are not replicated at the language pair level.

This is intended behavior. The changes done at the specific language pair level override the project-level Verification settings.

To revert to the project level settings, undo the setting changes at the language pair level - for example, remove all the words in the word list for the French language. The project will then revert to the project word list. After this, adding new words under Project Settings > Verification > QA Checker 3.0 > Word List will propagate to the specific language pair level.