Firstly, make sure you backup your registry and then do the following operations.

(1) Press Windows Button + R, type “regedit”, and then click OK.

(2) Navigate to the following registry subkey:
HKEY_LOCAL_MACHINE > SOFTWARE > Microsoft > Windows > CurrentVersion > SideBySid

(3) Right-click, select NEW > DWORD (32 bit) Value

(4) Type PreferExternalManifest, and then press ENTER.

(5) Right-click PreferExternalManifest, and then click Modify.

(6) Enter Value Data 1 and select Decimal.

(7) Click OK. Exit Registry Editor.

(8) Download the following file, unzip, then put the two contained files into the ZW3D installation directory (C:\Program Files\ZWSOFT\ZW3D 2017 Eng (x64))

JCD 4K Scaling Issues Files

(9) In order to launch JCD, you must now use the ZW3D shortcut, not the JCD shortcut.