If you’re worried about forensics, don’t do anything extremely sensitive on qubes and instead use tails persistence turned off for the specific sensitive operation and never save the info, learn the powers of verboten dictation which takes practice. There are cognitive memory techniques one can learn to remember, recall and dictate any information word for word.
To protect mildly sensitive operations in Qubes, make sure you keep the Qubes install powered off and unplugged when you’re not in a secure location or there are people around you who could grab your device while it is powered on. If it is powered off and has a 10 - 15 word diceware created passphrase not even a quantum computer could likely crack this. However keep the 10 to 15 words in memory only.
Also depending on who the adversary is, be aware that you may have an extremely secure system, but are your adversaries capable, willing, or would they enjoy brutally torturing your children in front of you in order to compel you to give up the passphrase? If so then look into “plausible deniability” that veracrypt hidden containers offers.
For now since it seems you’re just learning. Seriously don’t do anything sensitive until you get trained in the basics of “Information Security”. There’s tons of free courses on the matter. Get that finished first.
Look to typical classification levels used in most organizations that need to protect information by understanding the consequences to your organization should the stored data some how get leaked. Classified information - Wikipedia
You see in top secret = would cause “exceptionally grave damage” to security.
Secret = material would cause “serious damage” to security.
… And so on.
Does grave damage in your situation possibly mean death? Take the time to write our your own classification based on your unique circumstances. Use your custom designed classifcation levels to build out your Qube OS system and compartmentalized lifestyle according the classifications and risks you’ve taken the time to define.
Looking to these standards and partitioning your life accordingly by also understanding the need and value of compartmentalization which is part of the founding philosophy that has lead to the creation of Qubes. To Qube your life across different computers and to make it convenient by having all these computers in one area, laptop or desktop. But still separated via hardware level virtualization to make it harder for full compromise.
See more about this here: Getting started | Qubes OS
and here: Partitioning my digital life into security domains | The Invisible Things