why does yolov4 model(darknet) plot alots of bounding boxes around an object in one image?

Question

I'm using yolov4.cfg for training on my dataset.(I'm using this github repository: https://github.com/Abhi-899/YOLOV4-Custom-Object-Detection) after training 300 iteration, first I didn't get any bounding box for my images. after searching about this problem, found that I should decrease the threshold. so I changed my 3 yolo layers so:

[yolo]
mask = 6,7,8
anchors = 12, 16, 19, 36, 40, 28, 36, 75, 76, 55, 72, 146, 142, 110, 192, 243, 459, 401
classes=3
num=9
jitter=.3
ignore_thresh = 0.07 ############## .7
truth_thresh = 1 ############ 1
random=1
scale_x_y = 1.05
iou_thresh= 0.213 ##############0.213
cls_normalizer=1.0
iou_normalizer=0.07
iou_loss=ciou
nms_kind=greedynms
beta_nms=0.6
max_delta=5

now, I get alots of bounding boxes!!! what should I do? can any one help me? my output image is in below link: https://drive.google.com/file/d/1Jm7pAk8a89JgtPPeXLCLhRW_6hpV68l1/view?usp=sharing