Hello Harsha,
For fuse blow one can look below
Q&A: How to program i.MX6 eFUSE?
If one selected boot from fuses, this fuse selection can no be changed, since fuses are one time programmable.
https://www.nxp.com/webapp/sps/download/mod_download.jsp?colCode=IMX6DQ6SDLSRM&appType=moderatedWith...
Table. Boot MODE Pin Settings
Fuses select just boot options, after boot all modules remain fully
functional, that is :SD card will support SD3 and EMMC will support SD4.
Regards