Hello imtiazwighio and welcome to the Dubai visa
1a. If your wife is under your sponsorship and she changes jobs, it is not necessary to cancel and obtain a new Dubai residence visa
1b. If your wife is under your sponsorship and you change jobs, then you need to cancel her Dubai residence visa
, cancel your visa, get a new visa from new company, and then get a new Dubai residence visa for your wife.
2a. Your current employer can cancel your visa and your new employer will apply for a new employment and residence visa, or
2b. Your new employer might be able to get your current sponsorship transferred to them. The PRO of the new company should know what to do. In both cases you will need to submit passport, photos, medical test results, and copies of relevant qualifications to the Dubai labour office
2. See 1b.