I am not sure if ICA is processing your PR application. That means you cannot change job. If you change your job, you have to inform ICA and ICA will cancell your application, because your employer should sign in the form attached to your SPR approval letter and the company should be the same as the company who signed in your application form.
Otherwise, if you have not apply SPR, you can change your job, The social vist pass will give to you till the outcome of your ep application.
