So I've come across a problem more than once and it'd be a ton of help if I could get this figured out! So there are several instances where I've wanted to open a file with notepad or notepad++ to change values or something (mainly with videogames). The problem that I've come across is that sometimes when I open up a file such as a .PROPERTIES or .SII extension, instead of seeing the normal text like a ton of other people are capable of seeing, mine is jumbled and encoded.

For example, the file I am trying to edit "game.sii" is supposed to have a list something along the lines of
"total_distance: <number>
undamaged_cargo_row: <number>
service_visit_count: <number>
gas_station_visit_count: <number>
emergency_call_count: <number>
ai_crash_count: <number>
truck_color_change_count: <number>
red_light_fine_count: <number>
total_fuel_litres: <number>
total_fuel_price: <number>
money_account: <number>
current_career_level <number>
current_career_star_count <number>

but for me it looks like:
捓䍳ম꛴慼䭉묔匢腾ঔ淀쫇㵧䖚࠻喴ሧ鞳搆⒆혡ꘒ滻눕숐ፗꌖ䣾鶵攐齴鰪み嵼ⶆ㬆荇걕࠯ᅏȪ⨧挬摷吀궺ꓧ穘ↀㄅ涓縌藫Ṭ건䤾Ḑ眶츦䰈敝ԉ౧╁能ᦇᲑ褠 etc. etc.

I can't for the life of me understand why my notepad wouldn't read this file but so many other people have had success with it. Any help is appreciated & thanks for your time! :)

Have you tried to change the extension to something recognisable like ".txt", then edit the file, then change the extension back to ".sii"?

No dice. Still looks the exact same.