Visa 20 (Domestic) to Visa 18 (Working Visa) Procedure (2018)

First of all you need to find a sponsor which is  a private company who is willing to hire you , if they accept to hire you , then they need check how to transfer your visa 20  to 18.

Note : most of private companies wants employee who already has visa 18  , you need firstly to inform them that you are on visa 20.

Now who can accept you ?

Or : some companies or restaurants will agree to issue you 18 visa which is better than 20 but they may offer you a low salary because they know you do not  have many choices.(be careful)

My advice : find a local company who is looking for your experience and skills , negotiate with them about salary and other benefits. Ask them to issue you 18 visa. If they can not transfer you directly , then they may ask you to leave and they will send send you the new 18 visa.

Regards,