Updating a multidimensional Numpy Array Python

I am trying to add only to the right side of the array indx but I want to keep the left side of the array. How would I be able to get the Expected Output.

Code:

import numpy as np

number = 3
indx=np.array([[    0,     1],
 [    1,   765],
 [    0,  4355],
 [    1,  9364],
 [    0, 12110],
 [    1, 15233],
 [    0, 16246],
 [    1, 18889]])
indx = indx[:,1] + number

Output:

[    4   768  4358  9367 12113 15236 16249 18892]

Expected Output

[[    0     4]
 [    1   768]
 [    0  4358]
 [    1  9367]
 [    0 12113]
 [    1 15236]
 [    0 16249]
 [    1 18892]]

Answer

import numpy as np
 indx=np.array(
 [[    0,     1], 
 [    0,  4355],
 [    1,  9364],
 [    0, 12110],
 [    1, 15233],
 [    0, 16246],
 [    1, 18889]])
indx[:,1] = indx[:,1] + 3
print(indx)
[[    0     4]
 [    1   768]
 [    0  4358]
 [    1  9367]
 [    0 12113]
 [    1 15236]
 [    0 16249]
 [    1 18892]]