I got my recent CCR1036-8G-2S+ to use as my pppoe concentrator, and i see that on the site it says 6.24 is the latest version, but according to my box its already running 6.3, should i back it down to 6.24 or leave it at 6.3?
6.3 is older than 6.24
ok mind officially blown, so definitlly need to upgrade.
question in mikrotik naming convention is 6.24, 21 builds higher than 6.3?
Yes. The naming is exactly like this.
Are you new to software in general? 
It’s the usual . numbering, where “.” is just a separator between two numbers, not a decimal point.
Not necessarily. New versions are supposed to be better, they have new features, bugfixes, … but sometimes also new bugs. If you have new device and you’re just starting with it, then why not start with latest software. But later, when all is set up and in production, then “if it works, don’t touch it” is a golden rule.
Ya that second portion i understand i had issues with pppoe hence the upgrade And its a CCR and i know CCR’s are under heavy development especially for 7.0 (multiprocessing etc) whenever that comes out.
As for software development yes, i know major minor, but when presented as 6.3 and 6.21, i’ve had some software releases that release as 6.03 for clarity (helps when doing version checks as well as the version can be treated as a float 
) Now that i know its just Maj.Min. It clarifies