New Cutlass Day and some advice please

Firstly, thank you for all your advice in helping me choose my second EBMM guitar. I took delivery of this Cutlass BFR in Malibu Gold today:

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The guitar is gorgeous, but I need to adjust the string height – I have never done this before and I have no idea! There is noticeable buzzing up to about the 7th fret on the E, A and D strings. I do not mind a bit of string buzz, but the action does seem very low. No issue on the higher strings or on any strings higher than the 8th or 9th. I believe I need to turn the truss rod anticlockwise. I tried to use a hex key to do this, but it seemed very stiff, and I did not want to force it.