Help with replace specific column command

Input file:

ASD_QAW 12 A_@
AE_AQ 21 PA_123
ASDA_@ 23 ADA_AS
.
.

Output file:

ASD_QAW 12 A @
AE_AQ 21 PA 123
ASDA_@ 23 ADA AS
.
.

Do anybody know how to just specific and replace "_" in column 3 with tab delimiter (\t)?

Thanks for advice.

try..

 
awk '{gsub("_"," ",$3)}1'  filename

sed 's/\(.*\)_/\1 /' file