Hello, dear viccione009.
Thank you for your question.
To solve your problem you need to change some code from the plugin. Please find the file Total-Soft-Portfolio-settings.php. Edit the folder and on the line 3658 find the code
<input type="range" class="TotalSoft_Port_Range TotalSoft_Port_Rangepx" name="TotalSoft_PG_EG_21" id="TotalSoft_PG_EG_21" min="100" max="900" value="<?php echo $TotalSoft_PG_O_2_1[0]->TotalSoft_PG_1_21; ?>">
The place of this code put this one:
<input type="range" class="TotalSoft_Port_Range TotalSoft_Port_Rangepx" name="TotalSoft_PG_EG_21" id="TotalSoft_PG_EG_21" min="100" max="1200" value="<?php echo $TotalSoft_PG_O_2_1[0]->TotalSoft_PG_1_21; ?>">
Thank You.