The easy way will be to used the “replace values” function in the Power Query Editor but based on my data, I may not be able to use it so I will have to create a DAX formula. Let me show you the query editor first.

Click on “home -> transform data -> transform data”

Click on “transform -> replace values -> replace values”

A popup window will appear and you just have to fill the fields:

Now let´s do the DAX one. I will use 2 table examples, the first one always contains the word I am looking for. I will create 2 calculated columns by clicking on “new column” and put this formula:

SUBSTITUTE('table'[argument],"find value","new value")

NOTE:

• Change “table”, “argument”, “find value” and “new value” by yours
• For multiple values, change 'table'[argument] by the formula. For instance:
  SUBSTITUTE(SUBSTITUTE('table'[argument],"find value2","new value2"),"find value1","new value1")
  
• Alternatively, I can use the FIND function but it will replace the whole sentence and not the word: IF(FIND("find value",'table'[argument],1,BLANK()),"new value",'table'[argument])
  
• SUBSTITUTE/FIND are case sensitives so make sure “find value” is written as it must be

For case-insensitive (no matter how “find value” is written), I will use this formula:

REPLACE('table'[argument],SEARCH("find value",'table'[argument]),number,"new value")

NOTE: change “number” by the number of characters of “find value”. In my example, I am asking to find “inc003” which has 6 characters

Now, if in my table, some cells have not the value I am looking for, I will get an error as you can see in the picture below. To resolve it, I will use this formula:

IF(ISERROR(SEARCH("find value",'table'[argument])),'table'[argument],REPLACE('table'[argument],SEARCH("find value",'table'[argument]),number,"new value"))

For multiple values, I will use variables like that:

var frw1=IF(ISERROR(SEARCH("find value1",'table'[argument])),'table'[argument],REPLACE('table'[argument],SEARCH("find value1",'table'[argument]),number,"new value1"))
Return
IF(ISERROR(SEARCH("find value2",frw1)),frw1,REPLACE(frw1,SEARCH("find value2",frw1),number,"new value2"))             
              

For other case-insensitive options, read Power BI: search a word in different tables.