You are using Ambient sounds which are not intended for that purpose. Ambient sounds are things like music, wind/rain sounds.
Instead do this.
Create a new variable of type: Sound Cue. Compile and then set the Default Value of this new sound_cue variable.
In your blueprint editor window right click and search for Play Sound at Location. Plug your new sound cue variable into the Sound input. Fill the Location input as you wish (You could use Get Player Character → Get World Location). And then you can simultaneously fire these sounds.
