new job

As per the new system, how can I transfer my visa without authorisation of the current employer and without exiting the country? I have better offers from other companies. How do I go about this? 

I resigned from the company due to some personal issues and company cancelled my residency permit. I want to return to Qatar after settling my issues. So, do I need to obtain a no objection certificate from the company before leaving to get a new visa?

My first contract was for two years and it has expired. Now the company extended my contract for another year. My question is on expiry of the renewed contract by the end of this year and if I terminate the contract and cancel my visa, can I work in Qatar under another employer. 

I joined a company in 2007 with indefi nite contract term and the company was taken over by another in 2010. The same contract was extended by the new company. Again in 2016 another new company took over the previous one and my indefinite job contract term in 2016 mentions that “The start date of employment is deemed to be from 2007 while the contract effective date is from 2016”. Kindly clarify whether NOC is applicable in this case for taking any new employment in 2017.