My AMD Radeon R5 M335 is only running on 1GB rather thank 4GB as it should

I recently discovered that My AMD Radeon R5 M335 is only running on 1GB rather thank 4GB as it should.

 

All my drivers are up to date.

 

Here's a Snippet of my MSINFO file

 

Name AMD Radeon R5 M335

PNP Device ID PCI\VEN_1002&DEV_6660&SUBSYS_06B21028&REV_81\4&2370267D&0&00E0

Adapter Type AMD Radeon Graphics Processor (0x6660), Advanced Micro Devices, Inc. compatible

Adapter Description AMD Radeon R5 M335

Adapter RAM (1,048,576) bytes

Installed Drivers aticfx64.dll,aticfx64.dll,aticfx64.dll,amdxc64,aticfx32,aticfx32,aticfx32,amdxc32,atiumd64,atidxx64.dll,atidxx64.dll,atiumdag,atidxx32,atidxx32,atiumdva,atiumd6a.cap,atitmm64

Driver Version 21.19.128.4