Replace specific row in MySQL table

Initially, this is what we can see when I run SELECT * FROM block_custom;:

+-----+------------------+--------+-----------+
| bid | body             | info   | format    |
+-----+------------------+--------+-----------+
|   1 | Block1 body here | Block1 | full_html |
|   2 | Block2 body here | Block2 | full_html |
|   3 | Block3 body here | Block3 | full_html |
+-----+------------------+--------+-----------+

In order to replace info and bodyof table block_custom, I'm using below query:

update block_custom set info = replace(info,'Block2','Block2new');
update block_custom set body = replace(body,'body here','newbody here');

This is explanation of my query:

update [table_name] set [field_name] = replace([field_name],'[string_to_find]','[string_to_replace]');

When running this query to change body, it will replace in all row of column body.

How to make it change only in row 2 (bid 2)?