You must be doing something wrong. My heart value doesnt end in x74 or xF4 and neither do my IV values. If you're using GG, following jeronimo's guide for finding heart value, it should be a 8 digit hex number
Anyways, quick guide to IV modifying using GG
Step 0. Identify Unit with good ivs or ivs you want
Step 1: Find Heart Value. Copy the address. Go to address
Step 2: In hex calculator, Heart Value - 100
Step 3: Find that new value in the Go To (Arrow) function in GG
Step 4: Tick that line and the two lines below it. Save as dword
Step 5: Identify unit you want to modify ivs for
Step 6: Follow steps 1-3
Step 7: Copy saved line values as dword into new units line
Step 8: Change skills on characters you modified ivs for
Step 9: Restart the game
Step 10: Your IVs should be reflected by your new stats
Proof in pics all have +speed - res ivs