Use the following View menu options to switch between worksheets:

To move to the next worksheet tab, select Next Tab from the View menu.

To move to the previous worksheet tab, select Previous Tab from the View menu.

To switch to a specific worksheet:

If a small number of worksheets are open in different tabs, the names of the tabs are shown above the current worksheet. Click on the name of a worksheet to switch to it.

If many tabs are open, only the name of the current worksheet is shown. Click the name of the current worksheet.  A drop-down shows the open tabs in this window.

Select a worksheet tab to activate that worksheet.

Alternatively, use the More Windows option under the Window menu.