Power Tools sidebar offers a smart toolbar at the top for the most common operations. Each operation is available at a single click, with optional drop-down lists next to the default action. The only exceptions are Advanced Find and Replace and Function by Color: the tools take the entire sidebar with their settings.
Start Power Tools
Go to Add-ons > Power Tools > Start to open the add-on in Google Sheets:

You will see the Power Tools sidebar with the toolbar options right at its top.
Tip. You can run the Smart Toolbar add-ons directly from the Google Sheet menu:
Add-ons > Power Tools > Quick actions:

Search and replace data in Google Sheets
This two-step add-on performs a comprehensive search in the selected sheets, shows the list with the results, and allows you to browse, export, or replace the found entries:

Learn how to find and replace data in your sheets.
Count and sum values by fill and font color
Function by Color allows you to calculate records formatted in a certain way in any range.

Learn how to calculate cells by their colors.
Change case in Google Sheets
This one is the shortcut to changing case in all cells of interest.
First, tick off the Ignore formulas option if you want to prevent all formulas you may have from turning into values. The tool won't process such cells at all.
Then, select the necessary data in your spreadsheet, click on the tool's icon, and choose one of 5 cases:

Note. If you need to capitalize words/cells and there are some words in upper case within the range, please apply lowercase beforehand. This should be done in order to avoid corrupting any acronyms you may have.
Remove empty rows and columns
Select any cell in your table, click the tool icon and hit whatever you want to get rid of:

Freeze panes in a Google spreadsheet
- To leave the header rows and left columns visible when scrolling in large tables, select a cell right under and to the right of the area you want to remain visible and click on the Freeze panes icon:

This will lock all rows above and columns to the left of the selected cell.
- To unfreeze rows and columns, click on the down arrow next to the icon and pick the Unfreeze rows and columns option:

Calculate numbers in the selected columns or rows
The utility let's you get the formulas for the most common functions in a click. Even if you have multiple columns with numbers, simply select empty cells under those columns. The add-on will quickly process the data in each column and paste the correct result to each corresponding empty cell.
- Select columns with numbers that you want to count.
Tip. You can highlight a blank column next to rows of numbers to add calculations to each row.
- Click on the Calculate icon and pick one of 12 functions to add its formula under each column:

Unpivot table in Google Sheets
Use this tool to normalize a pivot table and get a flat list instead.
Select the range with your cross-tab table, click the icon with three dots on the Power Tools smart toolbar, then on the Unpivot Table icon itself, and have the resulting database list pasted to a new spreadsheet:

Flip cells, columns, or rows in a Google spreadsheet
Supposedly a simple task of flipping two adjacent cells involves a lot of copying and pasting. The Flip tool allows you to do this in just three clicks:
- Select adjacent cells you want to switch contents between.
Tip. To exchange data between rows or columns, you don't have to highlight the entire rows or columns: selecting cells from them and picking the options to flip entire rows/columns is enough.
- Click on the icon with three dots to see additional tools, then press the Flip icon, and pick the necessary option from the drop-down list:

Note. If you want to flip only the values and exclude the cell formatting, de-select the Include formatting option in the drop-down list by clicking on it.
Unmerge cells in a spreadsheet
The last but not least is the little assistant that helps you unmerge cells. You'll find it if you click the icon with three dots on the toolbar:

- To unmerge all selected cells, highlight the range that contains them and either click on the tool's icon or click on the down arrow next to the icon and pick the first option from the drop-down menu.
- To unmerge all cells on the sheet, select any cell on the spreadsheet of interest, click on the down arrow next to the icon, and pick the second option from the drop-down menu.
Responses
were is print two sides
Thank you for your question, Peter.
I'm sorry, but we don't have any add-on that would help you print from Google Sheets.
However, to print on two sides, you need to access your system printer settings before printing. Please follow the steps described here to do that correctly:
https://smallbusiness.chron.com/print-doublesided-google-docs-50784.html