Can you see different from these 3 screen captured
All was tested @Windows 10x64 (10.0.10586)

1. Win+PrtScr (Start+PrtScr) FullScreen Captured @1366*768 206KB 300DPI 24Bit



2 .PrtScr-Paste@Paint  FullScreen Captured @1366*768 160KB 96DPI 24Bit



3. Snagit PrtScr  FullScreen Captured @1366*768 145KB 96DPI 24Bit (Max Compressed, Program Default Setting)




Before edited was hidden in Spoil: compared contents  was tampered by cropped process
[Spoil] คลิกเพื่อดูข้อความที่ซ่อนไว้
1. Start+PrtScr (.png, 35.3kb)


2. 3rd party program, Snagit,  (.png, 35.3kb)


3. Windows's Paint (PrtScr paste ---> @Paint) (.png@24bit: Paint default), 96.7 KB (99,081 bytes)




My assumption: Your windows might be tampered by 3rd party program config.
Solution: Basic Step
for easy first step check (and auto fixed),
use this command, (run as admin @command prompt: "sfc / scannow"

before:


after: (no tampered found)



If this basic step not solve your problem, try next comments reply
edit: images sequence fixed, privacy fixed, "tempered" ---> "tampered" fixed