Ah. The cameras aren't overlapping and they aren't skewed, but the group image resolution isn't a good fit for your browser.
You can adjust the group image resolution here in
Blue Iris:
Blue Iris tries to fit your cameras as well as possible into the frame size you specify, while preserving aspect ratios and keeping the same order of cameras.
For best results you want the numbers in the resolution to be multiples of 16. So for example based on your UI2 screenshot, this might be a good fit: 1712 x 944. You don't want the frame size to be too big because the bigger it is, the lower your frame rate will be in the web interface.
You can adjust the width and height individually to tweak how the cameras are laid out, and to affect how much black space there may be around and between cameras.
Here is a list of multiples of 16 to help you out in dialing in the ideal frame size for your All cameras group:
16, 32, 48, 64, 80, 96, 112, 128, 144, 160, 176, 192, 208, 224, 240, 256, 272, 288, 304, 320, 336, 352, 368, 384, 400, 416, 432, 448, 464, 480, 496, 512, 528, 544, 560, 576, 592, 608, 624, 640, 656, 672, 688, 704, 720, 736, 752, 768, 784, 800, 816, 832, 848, 864, 880, 896, 912, 928, 944, 960, 976, 992, 1008, 1024, 1040, 1056, 1072, 1088, 1104, 1120, 1136, 1152, 1168, 1184, 1200, 1216, 1232, 1248, 1264, 1280, 1296, 1312, 1328, 1344, 1360, 1376, 1392, 1408, 1424, 1440, 1456, 1472, 1488, 1504, 1520, 1536, 1552, 1568, 1584, 1600, 1616, 1632, 1648, 1664, 1680, 1696, 1712, 1728, 1744, 1760, 1776, 1792, 1808, 1824, 1840, 1856, 1872, 1888, 1904, 1920, 1936, 1952, 1968, 1984, 2000, 2016, 2032, 2048, 2064, 2080, 2096, 2112, 2128, 2144, 2160, 2176, 2192, 2208, 2224, 2240, 2256, 2272, 2288, 2304, 2320, 2336, 2352, 2368, 2384, 2400