i mean how do i mix rows in FX loop block. lets assume FX loop block is in row 4, where it is now or instead of looper.
I looked at the screen shot of your preset. And my answer is the same, even if you put the effects loop where the looper block is.
Because of your use of the Send and Return blocks, your preset is really just using one grid line, except in the spot where that delay block goes around the effects loop.
You probably only have audio coming into grid 2 or grid 4 of your effects loop block. To test this, open the effects loop block and turn down the individual grid gains for 1,2,3, and 4. You're either going to cut your signal when you turn the #2 gain, or probably when you turn the #4 gain off inside the effects loop.
The only way to use the mixer inside the effects loop would be to shunt adjacent grid blocks into the effects loop.
For instance, you place a compressor, wah, drive, and amp on grid two. On the 5th row of your grid you place effects in parallel: chorus in grid 1, row 5, flanger in grid 2, row 5, phaser in grid 3 row five, with a reverb after it in row 6, pitch in grid 4, row 5, with another reverb after it. In row 7, of grid 2, you shunt all of those parallel block outputs backinto the input of the effects loop block that you place in grid 2, row 7. It would work the same regardless of which grid you place the effects loop, in row 7, provided the output shunts of those 4 parallel effects chains all go into the effects loop block.
Now you can control the mixture of your chorus, flange, phase/reverb, and pitch/reverb with the panning and mix knobs inside the effects loop block.
If you were to "go around" everything or not use grid 2 for an effect, so that your amp is the thing going into the effects loop on grid 2, you'd have unaffected amp in the grid 2 position of the effects loop, and chorus, phase, and pitch on the other matrixes of the effect loop block.