How to check memory size

To check the memory size of your Raspberry Pi, you can use the command:

$ free -m

or

$ cat /proc/meminfo

Both will show you the total memory.

Updating and upgrading Raspbian

To update software in Raspbian, enter the comamnd in Terminal:

$ sudo apt update
$ sudo apt full-upgrade

Note that full-upgrade is used in preference to a simple upgrade, as it also picks up any dependency changes that may have been made.

When using the above, the kernel and firmware will also be updated.

Reference: Raspberry Pi DOCUMENTATION > RASPBIAN > UPDATING