How do get my system to use the latest installed kernel?

I recently upgrade from Ubuntu 18.04 to 20.04 and then to 22.04. At least when going from 20.04 to 22.04 I got a prompt asking if I wanted to install the latest kernel, and I said yes (I can't remember what exactly happened when going from 18.04 to 22.04, to be perfectly honest).

The upgrades seemed to complete successfully, and I rebooted after each. However, it looks like the system is still using the old kernel despite the new old having been installed (as far as I can tell, anyway). Is there somewhere I have to specify what Kernel to use?

Here is some potentially relevant output:

$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description:    Ubuntu 22.04.1 LTS
Release:    22.04
Codename:   jammy
        
$ uname -a
Linux r13-003 4.15.0-122-lowlatency #124-Ubuntu SMP PREEMPT Thu Oct 15 13:40:54 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux
        
$ apt list --installed | grep linux
    
WARNING: apt does not have a stable CLI interface. Use with caution in scripts.
    
binutils-x86-64-linux-gnu/jammy-security,jammy-updates,now 2.38-4ubuntu2.1 amd64 [installed]
console-setup-linux/jammy,now 1.205ubuntu3 all [installed]
libselinux1-dev/jammy,now 3.3-1build2 amd64 [installed,automatic]
libselinux1/jammy,now 3.3-1build2 amd64 [installed]
linux-base/jammy,now 4.5ubuntu9 all [installed]
linux-firmware/jammy-updates,now 20220329.git681281e4-0ubuntu3.9 all [installed]
linux-generic/jammy-security,jammy-updates,now 5.15.0.58.56 amd64 [installed]
linux-headers-5.15.0-58-generic/jammy-security,jammy-updates,now 5.15.0-58.64 amd64 [installed,automatic]
linux-headers-5.15.0-58/jammy-security,jammy-updates,now 5.15.0-58.64 all [installed,automatic]
linux-headers-generic/jammy-security,jammy-updates,now 5.15.0.58.56 amd64 [installed]
linux-image-4.15.0-122-lowlatency/now 4.15.0-122.124 amd64 [installed,local]
linux-image-5.15.0-58-generic/jammy-security,jammy-updates,now 5.15.0-58.64 amd64 [installed,automatic]
linux-image-generic/jammy-security,jammy-updates,now 5.15.0.58.56 amd64 [installed]
linux-libc-dev/jammy-security,jammy-updates,now 5.15.0-58.64 amd64 [installed,automatic]
linux-modules-4.15.0-122-lowlatency/now 4.15.0-122.124 amd64 [installed,local]
linux-modules-5.15.0-58-generic/jammy-security,jammy-updates,now 5.15.0-58.64 amd64 [installed,automatic]
linux-modules-extra-5.15.0-58-generic/jammy-security,jammy-updates,now 5.15.0-58.64 amd64 [installed,automatic]
linux-sound-base/jammy,now 1.0.25+dfsg-0ubuntu7 all [installed,automatic]
python3-selinux/jammy,now 3.3-1build2 amd64 [installed,automatic]
util-linux/jammy,now 2.37.2-4ubuntu3 amd64 [installed]

I would like to run 5.15, which seems to be installed, but as you can see I'm currently on 4.15

Any help would be greatly appreciated!

A comment from ubfan1 correctly identified to problem--probably obvious to someone with more experience with Linux, but I'll post it here in case other neophytes are struggling with the same issue.

The problem was the line GRUB_DEFAULT="Advanced options for Ubuntu>Ubuntu, with Linux 4.15.0-122-lowlatency" in /etc/default/grub, which was specifying the 4.15.0 kernel. Changing this line to GRUB_DEFAULT=0 and running sudo update-grub causes the system to boot to the latest kernel on the next reboot. Thanks!