Technically, doing a HARD reboot (holding the power button for 10 secs), should NOT ever reset your BIOS back to factory settings; I’ve never heard of that happening before.
A soft reboot is using your UI or terminal to reboot the computer normally. A hard reboot risks you loosing data and/or corrupting files; especially in Windows.
BIOS (Basic Input/Output System), is firmware that is – literally – physically mounted to your motherboard; it has nothing to do with your operating system.
If Garuda disappears from your boot options, that’s your boot-loader (GRUB); or another problem – not your BIOS.
A hard-reboot should not reset your BIOS. I’m not sure what’s wrong, but something isn’t making sense here.
Does your BIOS sometimes seem to reset back to defaults, even when you have not done a hard reboot? Hard reboot being, holding down the power button for about 10 secs until it powers off.
HDD:
You said you’re using one physical HDD correct?
Are you using a GPT or MSDOS partition table?
If you have a single HDD, it’s likely “sda” in your partition manager. Please check to see if you’re using GPT or MSDOS parition table; if you don’t know.
fdisk -l /dev/sda
This command will list your partition table and partitions, please post the results…
For reference: fdisk - ArchWiki
On with Triple-Booting:
I’ve nearly always used dual-booting OS’s on computers, starting with Win95 and WinNT. But never triple booted.
This reference is meant to keep in mind that you’re using Windows with two different versions of Linux, but the reference is regarding dual-booting with 2 Linuxes; so keep in mind you got Windows too.
Dual booting two Linux distros (2019)
As mentioned in the above link; between two Linuxes, you can share a /home partition between the two – but not the root partition.
From personal experience, I would discourage you from using extended and logical partitions; if you’re using a MS-DOS partition table. I’ve had problems with data loss when using logical partitions.
IMO: If you really enjoy testing out Garuda, you might want to replace Ubuntu with Garuda; at least it’d save you the headache of trying to triple-boot – not to mention the excessive amount of partitions you’d have to use with 3 operating systems on one physical HDD.
Dead-set on triple-booting? Worst case: you could always install Garuda to a large USB drive or external HDD; with leaving room for making backups on a separate partition, if using an external HDD.
INFORMATION I NEED FROM YOU:
(1) The exact make and model # of your laptop (eg: Dell Inspiron 5735).
(2) BIOS version (you can get this from your BIOS screen (eg: F2); you’re looking for the version #.
(3) Helpful to also have your hard drive model # if possible.
(4) the results from the fdisk list from above.
Thanks. @johngilbert2000