Hey shreya,
As per my knowledge I guess your sign shouldn't be different everywhere. You should use only one signature and that should be kept official.also, as per your question, I guess you may change your signature as when you sign a job that will be official one. So, not sure about it but according to me you can change your signature while you are signing for a job.
Hope it helps.
Good luck.
Regular exam updates, QnA, Predictors, College Applications & E-books now on your Mobile