With so few details, it's quite unlikely that someone will be able to solve your problem. The more details you give, the better, in particular, how Windows 7 and 8 were installed: which one was first and another one added later, are they located on the different drives or on the different partitions of the same drive (not many laptops have two built-in drives like SSD and HDD), how your drive is partitioned if it is single, how your boot menu was set up and which menu items it has.
As for me, I use another way of dual boot via BIOS boot menu supported by motherboard manufacturer (ASUS in my case). It allows to select a boot device by pressing F8 key right after initial screen. One (primary) drive is M.2 SSD with Windows 8.1, another one is SATA SSD with Windows 10. So, the systems are completely separate, another drive is set offline in the disk management of every OS. If no F8 was pressed, the primary OS is started immediately without boot menu. Of course, primary drive can be chosen in BIOS setup.