not change yet vs not changed yet

Some examples from the web:

• Greta, I'm happy to discuss the menu with you, but I have not made any changes yet.
• The cause and the long-term effects of these changes are not yet known.
• Information received from Maltese citizens indicates that the changes have not yet been applied - let alone enforced.
• Numerous, large-scale changes, not yet completed and still inadequately known.
• It is merely that these changes have not yet come to an end.
• It appears that these changes have not yet been implemented and that the Maltese Government intends to seek a further derogation.
• In this generation we face a world of change not yet fully understood, in which we can either hasten or delay progress by the myriad of decisions that we take every day.
• What is more, the impact on the transport sector of the implementation of economic, social and financial measures to combat climate change has not yet been adequately examined or forecast.
• whereas the current EU budget is insufficient to achieve the climate objectives, since the political priority of combating climate change has not yet been furnished with the necessary budgetary appropriations,
• The precise budgetary implications of some of these changes are not yet determined and, therefore, are not fully incorporated into these estimates and will have to be taken into consideration during the first reading of the 2004 budget in the autumn.
• DQ. whereas the current EU budget is insufficient to achieve the climate objectives, since the political priority of combating climate change has not yet been furnished with the necessary budgetary appropriations,
• Carriers may not change the concessionary fares.
• This situation will not change after enlargement.
• Mocking will not change my opinion.
• HDL cholesterol and triglyceride concentrations did not change significantly.
• Pharmacokinetics were dose proportional and did not change over time.
• Postponing discharge until October would not change anything.
• The following keybindings assume you did not change the default settings.
• Abandoning your application here will not change the responsible country.
• However, the situation will not change overnight.

Some examples from the web:

• Not enough has changed yet in the world to justify changing that.
• Unemployment has not yet changed for the better.
• Have not yet changed the switch?
• Some of our main partners who have not yet changed their minds - Australia already has - will change their minds.
• However, the legal framework governing the approval of GMOs has not yet been changed.
• ANNEX VII The correlation table has not yet been changed to reflect Parliament's position.
• Thus far Ministers of Agriculture and the European Commission may have admitted that things may change in the distant future but they have not yet changed course entirely.
• Correlation table The correlation table has not yet been changed to reflect Parliament's position.
• Mrs Schierhuber, the Commission has not changed its opinion.
• Billions of development aid has not changed that.
• My feelings haven't changed yet.
• When these contracts lapse, it is likely that economic insights will have changed yet again.
• The Earth's climate changed yet again.
• I want you to write a paper exploring these issues presented almost 100 years ago and how they've changed or not changed since then.
• During each half-yearly, or as we suggest, yearly evaluation it might turn out that the order of states has changed yet again.
• the definition of target groups has not changed substantially,
• The ingredients and production method have not changed in approximately 150 years.
• The Committee notes that the list of prohibited or restricted substances is not changed by the proposed recast.
• The characteristics of the DEPB have not changed since the original investigation.
• The characteristics of the ITES have not changed since the original investigation.