I'm trying to animate the armature on a basic human shape I have created but every time I go into pose mode, move the bones, select them all and then click 'i', it inserts a key frame but when I run the animation, the bones stay in this NEW position from the beginning of the animation until the end.

I was wondering if anyone else has had this problem and if you could help me solve it please?

Thanks in advance.

i'm pretty sure this is intended. When inserting the first keyframe, the pose will be changed to this for the entire scene. But if you insert a second keyframe after the first with a different pose, it will become like this:

frame 1 to 1st keyframe: pose of 1st keyframe
frame after 1st keyfame to frame before 2nd keyframe: smooth transition
2nd keyframe to end: pose of 2nd keyframe

so the first step should be to insert a keyframe at frame 1 (LocRotScale), to start with the base pose (i believe you missed this)

if you wanna make the 1st frame's pose like the rest pose, set current frame to 1 on timeline, then click the menu of the 3d viewport: Pose > Clear Transform > All (or just rotation + scale, in case you wanna retain the location etc.). Finally, insert keyframe, e.g. LocRotScale
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