I have downloaded OLX app and presently it is in internal memory. When I try to move this app to SD card it says "Insufficient space. Can't move to SD card". Please help. I am using Huawei Honor 4X handset now.
There are some cheap cards that are actually hacked - they lie their capacity to the system. I'd suggest you to make a test to check if you didn't get a fake SD card. This site recommends you to install H2testw in a Windows computer or SD Insight Android app to test the card's properties. Another option for newer Android is
True SD Card Capacity & Speed Test: Pro Version app.
Unfortunately, cheap SD cards most of the time mean fake SD cards - they often have a much smaller capacity than what they announce (and smaller than all the OS recognizes), causing data corruption when you try to store more data than what those fake cards actually supports - among other problems...