Are Navy jobs Permanent or can they switch ?

Well this is the deal I went to see a naval reserve recruiter then took the pre test at the office and he was like cool you did well on it meps should be no prob so I then went to meps and did all the testing physical was good only thing was my eyes are not 20/20 correctable and the rest was fine and then came time to do the job placing and I told the recruiter I want to go with the MA program then they cam and told me I was just a little bit shy on my meps score to nab that job and told me no big deal retake the test .well few days went by and I git a call saying he has a job I may place to git but it was full time and I told him I only want a reserve job till I finish school and then I git a call back today he has a CS job cooking is not what I wanted to do but I dont mind to do it or any job they give me going to serve my country no-matter what the job is but would like to know if i prove my self in bootcamp if i might git a chance to go MA or something like that kinda wanted to do something more tactical but cant take buds bc I dont have 20/20 ? If not I still plan to join and go in the am to put my name on the contract thanks and god bless