It doesn't matter how competent you are, or how hard you work, or how clearly you communicate, or whether your job title says "senior", or whether you put your heart and soul into the job; if the big boss doesn't like you, you're gone. I learned that the hard way. A better boss might have said "if you express that opinion a third time, I'll fire you," or "if X isn't done in the next two weeks, I'll fire you," but this is not that boss. This boss does drop hints, which you need to pick up on the first time. Otherwise you'll find yourself strangled from behind one day. As your fingers claw at the wire and your legs flail helplessly, a calm voice will say "we decided you aren't a good fit for this life; we wish you luck in the next one."
The good news is that you can be successful here by following the unwritten rules that I broke:
1. Your superiors are always right. Hence the term "superior". Your idea isn't worth a cost-benefit analysis since it won't make a profit within this year, pre-existing customers aren't asking for it, and most importantly, tell him he's right, apologize, and don't bring it up again.
2. Doing it fast is better than doing it well. (I thought this rule had been revised, but my pink slip suggests otherwise.)
3. You need not understand it before you change it: understanding takes too long. What matters is figuring out if still works afterward.....
4. Stick with assigned tasks. Unpaid overtime for extra tasks isn't "taking initiative", it's insubordination; overtime is mostly for assigned tasks.
5. Documentation is allowed, but not important (it's just one more thing to maintain).
To get along with your coworkers, keep in mind that their personalities fit into the unwritten rules (otherwise they'd be gone - I heard I'm not the first to be axed).