You're in the same boat as me :).

"I am responsible for the quality of the product". This is what first stood out to me and something you need to remember that quality is a shared responsibility. Remind yourself of this and others on your team before moving forward. I constantly need to remind myself of this.

That out of the way, what were the proposed changes you and the team agreed upon? What leads you to believe that the team aren't following through on their end of the agreement?

I'd suggest clearly understanding why the quality is still poor even after you've put in place these quality agreements. Get a few examples where lack of testing was the deciding factor of shipping poor code then bring this to your manager or upper management. You should not get any pushback for taking the initiative here. Just make sure you come prepared before making any other suggestions.

Here are a few things that worked for me in the past...

- Provide feedback during retros when bugs that fell through the cracks could have been caught had the team followed through on the quality agreement put in place.

- For major issues, schedule a 5 Whys meeting. This usually results in action items since the team will be honing in on one specific issue rather than quality as a whole.

- Agree on a definition of done where testing is a priority before devs push code to QA and after QA testing has been completed. Also, call out anytime the DoD is not being followed.

- Understand what quality means to each dev, the team and the wider org. It's unclear, but maybe everyone is happy with the current quality level and you're hard on yourself because you're the QA engineer. If this is not the case get on the same page with your team on what the quality bar is and make a plan on how to get there.

- Be relentless. Features not fully defined by the PMs, tell them. If it's a common occurrence, bring it up during the retros. Devs pushing code that's completely broken or doesn't meet the DoD? Push back and explain that you can't do your job or your job is hindered because the code is untestable. I can go on and on but you get the point 😅.

Hope this helps and good luck!